I&#39;m trying to rotate a `UIImageView` 360 degrees, and have looked at several tutorials online. I could get none of them working, without the `UIView` either stopping, or jumping to a new position.

* How can I achieve this?

The latest thing I&#39;ve tried is:

    [UIView animateWithDuration:1.0
						  delay:0.0
						options:0
					 animations:^{
						 imageToMove.transform = CGAffineTransformMakeRotation(M_PI);
					 } 
					 completion:^(BOOL finished){
						 NSLog(@&quot;Done!&quot;);
					 }];

But if I use 2*pi, it doesn&#39;t move at all (since it&#39;s the same position). If I try to do just pi (180 degrees), it works, but if I call the method again, it rotates backwards.

**EDIT**:

    [UIView animateWithDuration:1.0
						  delay:0.0
						options:0
					 animations:^{
						 [UIView setAnimationRepeatCount:HUGE_VALF];
						 [UIView setAnimationBeginsFromCurrentState:YES];
						 imageToMove.transform = CGAffineTransformMakeRotation(M_PI);
					 } 
					 completion:^(BOOL finished){
						 NSLog(@&quot;Done!&quot;);
					 }];

doesn&#39;t work either. It goes to `180` degrees, pauses for a split second, then resets back to `0` degrees before it starts again.


UIView Infinite 360 degree rotation animation?

Is it possible to cancel a `UIView` animation while it is in progress? Or would I have to drop to the CA level?

i.e. I&#39;ve done something like this (maybe setting an end animation action too):

    [UIView beginAnimations:nil context:NULL];
    [UIView setAnimationDuration:duration];
    [UIView setAnimationCurve: UIViewAnimationCurveLinear];
    // other animation properties

    // set view properties

    [UIView commitAnimations];

But before the animation completes and I get the animation ended event, I want to cancel it (cut it short). Is this possible? Googling around finds a few people asking the same question with no answers - and one or two people speculating that it can&#39;t be done.

Cancel a UIView animation?

I&#39;m looking to perform a perspective transform on a UIView (such as seen in coverflow)

Does anyonew know if this is possible? 

I&#39;ve investigated using `CALayer` and have run through all the pragmatic programmer Core Animation podcasts, but I&#39;m still no clearer on how to create this kind of transform on an iPhone.

Any help, pointers or example code snippets would be really appreciated!

How do I apply a perspective transform to a UIView?

What is considered best practice for animating view transitions on the iPhone? 

For example, the `ViewTransitions` sample project from apple uses code like:

    CATransition *applicationLoadViewIn = [CATransition animation];
	[applicationLoadViewIn setDuration:1];
	[applicationLoadViewIn setType:kCATransitionReveal];
	[applicationLoadViewIn setTimingFunction:[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseIn]];
	[[myview layer] addAnimation:applicationLoadViewIn forKey:kCATransitionReveal];

but there are also code snippets floating around the net that look like this: 

    [UIView beginAnimations:nil context:nil];
    [UIView setAnimationDuration:0.75];
    [UIView setAnimationDelegate:self];
    [UIView setAnimationTransition:UIViewAnimationTransitionFlipFromRight forView:myview cache:YES];
    [myview removeFromSuperview];
    [UIView commitAnimations];

 

What is the best approach? If you could provide a snippet as well it&#39;d be much appreciated. 

**NOTE:** I&#39;ve been unable to get the second approach to work correctly. 


iPhone UIView Animation Best Practice

I&#39;ve got a layer with some complex drawing code in its -drawInContext: method. I&#39;m trying to minimize the amount of drawing I need to do, so I&#39;m using -setNeedsDisplayInRect: to update just the changed parts. This is working splendidly. However, when the graphics system updates my layer, it&#39;s transitioning from the old to the new image using a cross-fade. I&#39;d like it to switch over instantly.

I&#39;ve tried using CATransaction to turn off actions and set the duration to zero, and neither work. Here&#39;s the code I&#39;m using:

	[CATransaction begin];
	[CATransaction setDisableActions: YES];
	[self setNeedsDisplayInRect: rect];
	[CATransaction commit];

Is there a different method on CATransaction I should use instead (I also tried -setValue:forKey: with kCATransactionDisableActions, same result).


Disabling implicit animations in -[CALayer setNeedsDisplayInRect:]

I am animating a `CALayer` along a `CGPath` (QuadCurve) quite nicely in iOS. But I&#39;d like to use a more interesting easing function than the few [provided][1] by Apple (EaseIn/EaseOut etc). For instance, a bounce or elastic function. 

These things are possible to do with MediaTimingFunction (bezier):

![enter image description here][2]

But I&#39;d like to create **timing functions** that are more complex. Problem is that media timing seems to require a cubic bezier which is not powerful enough to create these effects:

[![enter image description here][4]][4]  
&lt;sub&gt;(source: [sparrow-framework.org](http://wiki.sparrow-framework.org/_media/manual/transitions.png))&lt;/sub&gt;  


The [code][3] to create the above is simple enough in other frameworks, which makes this very frustrating. Note that the curves are mapping input time to output time (T-t curve) and not time-position curves. For instance, *easeOutBounce(T) = t* returns a new *t*. Then that *t* is used to plot the movement (or whatever property we should animate).

*So, I&#39;d like to create a complex custom `CAMediaTimingFunction` but I have no clue how to do that, or if it&#39;s even possible? Are there any alternatives?*

**EDIT:**

Here is a concrete example in to steps. Very educational :)

1. I want to animate an object along a line from point *a* to *b*, but I want it to &quot;bounce&quot; its movement along the line using the easeOutBounce curve above. This means it will follow the exact line from *a* to *b*, but will accelerate and decelerate in a more complex way than what is possible using the current bezier-based CAMediaTimingFunction. 

2. Lets make that line any arbitrary curve movement specified with CGPath. It should still move along that curve, but it should accelerate and decelerate the same way as in the line example.

In theory I think it should work like this:

Lets describe the movement curve as a keyframe animation *move(t) = p*, where *t* is time [0..1], *p* is position calculated at time *t*. So *move(0)* returns the position at the start of curve, *move(0.5)* the exact middle and *move(1)* at end. Using a an timing function *time(T) = t* to provide the *t* values for *move* should give me what I want. For a bouncing effect, the timing function should return the same *t* values for *time(0.8)* and *time(0.8)* (just an example). Just replace the timing function to get a different effect.

(Yes, it&#39;s possible to do line-bouncing by creating and joining four line segments which goes back and forth, but that shouldn&#39;t be necessary. After all, it&#39;s just a simple linear function which maps *time* values to positions.)


I hope I&#39;m making sense here.

  [1]: https://developer.apple.com/library/archive/#documentation/Cocoa/Reference/CAMediaTimingFunction_class/Introduction/Introduction.html#//apple_ref/doc/constant_group/Predefined_Timing_Functions
  [2]: https://i.stack.imgur.com/cxJuW.png
  [3]: https://github.com/PrimaryFeather/Sparrow-Framework/blob/master/sparrow/src/Classes/SPTransitions.m#L86
  [4]: https://i.stack.imgur.com/IIZqM.png

How to create custom easing function with Core Animation?

I&#39;m porting a block of code from an iOS4 project to iOS5 and I&#39;m having some troubles with ARC.  The code generates a PDF from a screen capture.

PDF Generation Code
&lt;pre&gt;&lt;code&gt;UIView *captureView;
...
NSMutableData *pdfData = [NSMutableData data];
UIGraphicsBeginPDFContextToData(pdfData, captureView.bounds, nil);
UIGraphicsBeginPDFPage();
CGContextRef pdfContext = UIGraphicsGetCurrentContext();
[captureView.layer renderInContext:pdfContext];
UIGraphicsEndPDFContext();&lt;/code&gt;&lt;/pre&gt;

The renderInContext line
&lt;pre&gt;&lt;code&gt;[captureView.layer renderInContext:pdfContext];&lt;/code&gt;&lt;/pre&gt;
generates the following error.
&lt;pre&gt;&lt;code&gt;Automatic Reference Counting issue
Receiver type &#39;CALayer&#39; for instance message is a forward declaration&lt;/code&gt;&lt;/pre&gt;

Any ideas what is going on here?

What does &quot;Receiver type &#39;CALayer&#39; for instance message is a forward declaration&quot; mean here?

I had a problem where I had a series of overlapping CATransition / CAAnimation sequences, all of which I needed to perform custom operations when the animations stopped, but I only wanted one delegate handler for animationDidStop.

However, I had a problem, there didn&#39;t appear to be a way to uniquely identify each CATransition / CAAnimation in the animationDidStop delegate.

I solved this problem via the key / value system exposed as part of CAAnimation.

When you start your animation use the setValue method on the CATransition / CAAnimation to set your identifiers and values to use when animationDidStop fires:

    -(void)volumeControlFadeToOrange
    {	
    	CATransition* volumeControlAnimation = [CATransition animation];
    	[volumeControlAnimation setType:kCATransitionFade];
    	[volumeControlAnimation setSubtype:kCATransitionFromTop];
    	[volumeControlAnimation setDelegate:self];
    	[volumeControlLevel setBackgroundImage:[UIImage imageNamed:@&quot;SpecialVolume1.png&quot;] forState:UIControlStateNormal];
    	volumeControlLevel.enabled = true;
    	[volumeControlAnimation setDuration:0.7];
    	[volumeControlAnimation setValue:@&quot;Special1&quot; forKey:@&quot;MyAnimationType&quot;];
    	[[volumeControlLevel layer] addAnimation:volumeControlAnimation forKey:nil];	
    }

    - (void)throbUp
    {
    	doThrobUp = true;
    	
    	CATransition *animation = [CATransition animation];	
    	[animation setType:kCATransitionFade];
    	[animation setSubtype:kCATransitionFromTop];
    	[animation setDelegate:self];
    	[hearingAidHalo setBackgroundImage:[UIImage imageNamed:@&quot;m13_grayglow.png&quot;] forState:UIControlStateNormal];
    	[animation setDuration:2.0];
    	[animation setValue:@&quot;Throb&quot; forKey:@&quot;MyAnimationType&quot;];
    	[[hearingAidHalo layer] addAnimation:animation forKey:nil];
    }

In your animationDidStop delegate:

    - (void)animationDidStop:(CAAnimation *)theAnimation finished:(BOOL)flag{
    	
        NSString* value = [theAnimation valueForKey:@&quot;MyAnimationType&quot;];
        if ([value isEqualToString:@&quot;Throb&quot;])
        {
           //... Your code here ...
           return;
        }
    	
    	
        if ([value isEqualToString:@&quot;Special1&quot;])
        {
           //... Your code here ...
           return;
        }
    
        //Add any future keyed animation operations when the animations are stopped.
     }

		

The other aspect of this is that it allows you to keep state in the key value pairing system instead of having to store it in your delegate class. The less code, the better.

Be sure to check out the [Apple Reference on Key Value Pair Coding][1].

Are there better techniques for CAAnimation / CATransition identification in the animationDidStop delegate?

Thanks,
--Batgar


  [1]: http://17.254.2.129/iphone/library/documentation/Cocoa/Conceptual/CoreAnimation_guide/Articles/KVCAdditions.html

How to identify CAAnimation within the animationDidStop delegate?

I&#39;ve made a `CALayer` with an added `CATextLayer` and the text comes out blurry.  In the docs, they talk about &quot;sub-pixel antialiasing&quot;, but that doesn&#39;t mean much to me.  Anyone have a code snippet that makes a `CATextLayer` with a bit of text that is clear?

Here&#39;s the text from Apple&#39;s documentation:

&gt; Note: CATextLayer disables sub-pixel antialiasing when rendering text.
&gt; Text can only be drawn using sub-pixel antialiasing when it is
&gt; composited into an existing opaque background at the same time that
&gt; it&#39;s rasterized. There is no way to draw subpixel-antialiased text by
&gt; itself, whether into an image or a layer, separately in advance of
&gt; having the background pixels to weave the text pixels into. Setting
&gt; the opacity property of the layer to YES does not change the rendering
&gt; mode.

The second sentence implies that one can get good looking text if one `composites` it into an `existing opaque background at the same time that it&#39;s rasterized.`  That&#39;s great, but how do I composite it and how do you give it an opaque background and how do you rasterize  it?

The code they use in their example of a Kiosk Menu is as such: (It&#39;s OS X, not iOS, but I assume it works!)

    NSInteger i;
    for (i=0;i&lt;[names count];i++) {
        CATextLayer *menuItemLayer=[CATextLayer layer];
        menuItemLayer.string=[self.names objectAtIndex:i];
        menuItemLayer.font=@&quot;Lucida-Grande&quot;;
        menuItemLayer.fontSize=fontSize;
        menuItemLayer.foregroundColor=whiteColor;
        [menuItemLayer addConstraint:[CAConstraint
             constraintWithAttribute:kCAConstraintMaxY
                          relativeTo:@&quot;superlayer&quot;
                           attribute:kCAConstraintMaxY
                              offset:-(i*height+spacing+initialOffset)]];
        [menuItemLayer addConstraint:[CAConstraint
             constraintWithAttribute:kCAConstraintMidX
                          relativeTo:@&quot;superlayer&quot;
                           attribute:kCAConstraintMidX]];
        [self.menuLayer addSublayer:menuItemLayer];
    } // end of for loop 

Thanks!

---

EDIT: Adding the code that I actually used that resulted in blurry text.  It&#39;s from a related question I posted about adding a `UILabel` rather than a `CATextLayer` but getting a black box instead.  `http://stackoverflow.com/questions/3818676/adding-a-uilabels-layer-to-a-calayer-and-it-just-shows-black-box`

    CATextLayer* upperOperator = [[CATextLayer alloc] init];
    CGColorSpaceRef space = CGColorSpaceCreateDeviceRGB();
    CGFloat components1[4] = {1.0, 1.0, 1.0, 1.0};
    CGColorRef almostWhite = CGColorCreate(space,components1);
    CGFloat components2[4] = {0.0, 0.0, 0.0, 1.0};
    CGColorRef almostBlack = CGColorCreate(space,components2);
    CGColorSpaceRelease(space);
    upperOperator.string = [NSString stringWithFormat:@&quot;13&quot;];
    upperOperator.bounds = CGRectMake(0, 0, 100, 50);
    upperOperator.foregroundColor = almostBlack;
    upperOperator.backgroundColor = almostWhite;
    upperOperator.position = CGPointMake(50.0, 25.0);
    upperOperator.font = @&quot;Helvetica-Bold&quot;;
    upperOperator.fontSize = 48.0f;
    upperOperator.borderColor = [UIColor redColor].CGColor;
    upperOperator.borderWidth = 1;
    upperOperator.alignmentMode = kCAAlignmentCenter;
    [card addSublayer:upperOperator];
    [upperOperator release];
    CGColorRelease(almostWhite);
    CGColorRelease(almostBlack);

---

EDIT 2:  See my answer below for how this got solved.  sbg.

How to get text in a CATextLayer to be clear

While investigating a memory leak I discovered a problem related to the technique of calling `setRootViewController:` inside a transition animation block:

    [UIView transitionWithView:self.window
                      duration:0.5
                       options:UIViewAnimationOptionTransitionFlipFromLeft
                    animations:^{ self.window.rootViewController = newController; }
                    completion:nil];

If the old view controller (the one being replaced) is currently presenting another view controller, then the above code does not remove the presented view from the view hierarchy.

That is, this sequence of operations...

1. X becomes Root View Controller
2. X presents Y, so that Y&#39;s view is on screen
3. Using `transitionWithView:` to make Z the new Root View Controller

...looks OK to the user, but the Debug View Hierarchy tool will reveal that Y&#39;s view is still there behind Z&#39;s view, inside a `UITransitionView`. That is, after the three steps above, the view hierarchy is:

- UIWindow
   - UITransitionView
      - UIView (Y&#39;s view)
   - UIView (Z&#39;s view)

I suspect this is a problem because, at the time of the transition, X&#39;s view isn&#39;t actually part of the view hierarchy.

If I send `dismissViewControllerAnimated:NO` to X immediately before `transitionWithView:`, the resulting view hierarchy is:

- UIWindow
   - UIView (X&#39;s view)
   - UIView (Z&#39;s view)

If I send `dismissViewControllerAnimated:` (YES or NO) to X, then perform the transition in the `completion:` block, then the view hierarchy is correct. Unfortunately, that interferes with the animation. If animating the dismissal, it wastes time; if not animating, it looks broken.

I&#39;m trying some other approaches (e.g., making a new container view controller class to serve as my root view controller) but haven&#39;t found anything that works. I&#39;ll update this question as I go.

The ultimate goal is to transition from the presented view to a new root view controller directly, and without leaving stray view hierarchies around.

Leaking views when changing rootViewController inside transitionWithView

i&#39;m trying to make a UIView shake when a button is pressed.

I am adapting the code I found on [http://www.cimgf.com/2008/02/27/core-animation-tutorial-window-shake-effect/][1].

However, by trying to adapt the following code to shake a UIView, it does not work:

    - (void)animate {
        const int numberOfShakes = 8;
	    const float durationOfShake = 0.5f;
	    const float vigourOfShake = 0.1f;
	
        CAKeyframeAnimation *shakeAnimation = [CAKeyframeAnimation animation];
	
	    CGRect frame = lockView.frame;
	
        CGMutablePathRef shakePath = CGPathCreateMutable();
        CGPathMoveToPoint(shakePath, NULL, CGRectGetMinX(frame), CGRectGetMinY(frame));
	
	    for (int index = 0; index &lt; numberOfShakes; ++index) {
		    CGPathAddLineToPoint(shakePath, NULL, CGRectGetMinX(frame) - frame.size.width * vigourOfShake, CGRectGetMinY(frame));
		
		    CGPathAddLineToPoint(shakePath, NULL, CGRectGetMinX(frame) + frame.size.width * vigourOfShake, CGRectGetMinY(frame));
	    }
	
        CGPathCloseSubpath(shakePath);
	
        shakeAnimation.path = shakePath;
        shakeAnimation.duration = durationOfShake;
	
	
    	[lockView.layer addAnimation:shakeAnimation forKey:@&quot;frameOrigin&quot;];

    }


  [1]: http://www.cimgf.com/2008/02/27/core-animation-tutorial-window-shake-effect/

UIView shake animation

For some reason, when I try to animate `textColor`, it won&#39;t work. The `textColor` just suddenly changes from A to B. Is it possible to animate it, for example, red to black?

How to animate the textColor property of an UILabel?

I&#39;m trying to drag a `CALayer` in an iOS app.

As soon as I change its position property it tries to animate to the new position and flickers all over the place:

```
 layer.position = CGPointMake(x, y)
```

How can I move `CALayers` instantly? I can&#39;t seem to get my head around the Core Animation API.

How do you move a CALayer instantly (without animation)

This looks like it should work, but doesn&#39;t. The color turns green at once.

    self.labelCorrection.backgroundColor = [UIColor whiteColor];
    [UIView animateWithDuration:2.0 animations:^{
        self.labelCorrection.backgroundColor = [UIColor greenColor];
    }];




How to animate the background color of a UILabel?

I am developing a commerce application. When I add an item to the shopping cart, I want to create an effect where an image of the item follows a curved path and ends up at the cart tab.

How can I create an animation of an image along a curve like this?

How can I animate the movement of a view or image along a curved path?

I&#39;m wondering where the callbacks are (or if there are anything) for animations in a CALayer. Specifically, for implied animations like altering the frame, position, etc. In a UIView, you could do something like this:

	[UIView beginAnimations:@&quot;SlideOut&quot; context:nil];
	[UIView setAnimationDuration:.3];
	[UIView setAnimationDelegate:self];
	[UIView setAnimationDidStopSelector:@selector(animateOut:finished:context:)];
	CGRect frame = self.frame;
	frame.origin.y = 480;
	self.frame = frame;
	[UIView commitAnimations];

Specifically, the `setAnimationDidStopSelector` is what I want for an animation in a CALayer. Is there anything like that?

TIA.

Animation End Callback for CALayer?

Any ideas as to how Apple implemented the &quot;slide to unlock&quot; (also, &quot;slide to power off&quot; is another identical example) animation?

I thought about some sort of animating mask - but masking is not available on the iPhone OS for performance reasons.

Is there some private API effect (like SuckEffect) that they might have used? A spotlight type of effect?  Some Core Animation thing?

Edit:
It&#39;s definitely not a series of stills.  I&#39;ve seen examples of being edit a plist value or something and customize the string on jailbroken iphones.

iPhone &quot;slide to unlock&quot; animation

I&#39;m struggling with conceptualizing animations with a **CALayer** as opposed to **UIView&#39;s** own animation methods. Throw &quot;**Core Animation**&quot; into this and, well, maybe someone can articulate these concepts from a high level so I can better visualize what&#39;s happening and why I&#39;d want to migrate UIView animations (which I&#39;m quite familiar with now) to CALayer animations on the iPhone. Every view in Cocoa-Touch automatically gets a layer. And, it seems, you can animate one *and/or the other?!?* Even mix them together?!? But why? Where&#39;s the line? What&#39;s the pro/con to each?

The Core Animation Programming Guide immediately jumps into Layer &amp; Timing Classes and I think need to take a step back and understand why these varied pieces exist and how relate to each other.

UIView animation vs CALayers

I have a class which is a subclass of `UIView`. I am able to draw stuff inside the view either by implementing the `drawRect` method, or by implementing `drawLayer:inContext:` which is a delegate method of `CALayer`. 

I have two questions:

 1. How to decide which approach to use? Is there a use case for each one?
 2. If I implement `drawLayer:inContext:`, it is called (and `drawRect` isn&#39;t, at least as far as putting a breakpoint can tell), even if I don&#39;t assign my view as the `CALayer` delegate by using:

 `[[self layer] setDelegate:self];` 

 how come the delegate method is called if my instance is not defined to be the layer&#39;s delegate? and what mechanism prevents `drawRect` from being called if `drawLayer:inContext:` is called?

iOS: Using UIView&#39;s &#39;drawRect:&#39; vs. its layer&#39;s delegate &#39;drawLayer:inContext:&#39;

I&#39;ve been trying to figure out a way to draw segments as illustrated in the following image:

![enter image description here][1]

I&#39;d like to:

 1. draw the segment
 2. include gradients
 3. include shadows
 4. animate the drawing from 0 to n angle

I&#39;ve been attempting to do this with `CGContextAddArc` and similar calls but not getting very far.

Can anyone help ?


  [1]: http://i.stack.imgur.com/oadFr.png

Draw segments from a circle or donut

I&#39;m trying to animate the change of the `cornerRadius` of a `UIView` instance `layer`, but the variation of the `cornerRadius` takes place immediately.

Here&#39;s the code:

    UIView *view = [[UIView alloc] initWithFrame:CGRectMake(10, 10, 100, 100)];
    view.layer.masksToBounds = YES;
    view.layer.cornerRadius = 10.0;
    [UIView animateWithDuration:1.0 animations:^{
        
        [view.layer.cornerRadius = 0.0;
        
    }];

Thanks everybody who is going to give me any tips.

#### **EDIT:**
I managed to animate this property using `Core Animation`, using a `CABasicAnimation`. 

    CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@&quot;cornerRadius&quot;];
    animation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear];
    animation.fromValue = [NSNumber numberWithFloat:10.0f];
    animation.toValue = [NSNumber numberWithFloat:0.0f];
    animation.duration = 1.0;
    [viewToAnimate.layer addAnimation:animation forKey:@&quot;cornerRadius&quot;];
    [animation.layer setCornerRadius:0.0];


UIView animateWithDuration doesn&#39;t animate cornerRadius variation

A `UIView` has a `CALayer`. That&#39;s pretty sure. But both seem to provide something that means the same thing.

If I&#39;d set `clipsToBounds=YES`, would this also set the layer&#39;s `masksToBounds=YES`? Why different names? Anyone knows?

How is the relation between UIView&#39;s clipsToBounds and CALayer&#39;s masksToBounds?

I can add a border to a CALayer in this way:

	[webView.layer setBorderColor: [[UIColor colorWithRed:0.6 green:0.7 blue:0.2 alpha:1] CGColor]];
	[webView.layer setBorderWidth: 2.75];	

But is it possible to add a border only at one side? I only need a border at the bottom. Or can I reach this with other properties, e.g. frame, bounds, mask, ...?

![enter image description here][1]

Thanks for your help!

---------

@Control-V

			UIWebView *webView = [[UIWebView alloc] init];
			CALayer *webViewLayer = webView.layer;
			
			// now you can do a lot of stuff like borders:
			[webViewLayer setBorderColor: [[UIColor greenColor] CGColor]];
			[webViewLayer setBorderWidth: 2.75];  	

		
			
Have a look at the CALayer documentation:
https://developer.apple.com/documentation/quartzcore/calayer

And have a look here:
http://iosdevelopertips.com/cocoa/add-rounded-corners-and-border-to-uiwebview.html

  [1]: https://i.stack.imgur.com/zn3eu.jpg

CALayer: add a border only at one side

I have trouble with deleting all of layer&#39;s sublayers. I currently do this manually, but that brings unnecessary clutter. I found many topics about this in google, but no answer.

I tried to do something like this:

&lt;pre&gt;
for(CALayer *layer in rootLayer.sublayers)
{
    [layer removeFromSublayer];
}
&lt;/pre&gt;

but it didn&#39;t work.

Also, i tried to clone rootLayer.sublayers into separate NSArray, but result was the same.

Any ideas?

Edit:

I thought it works now, but I was wrong. It works good with CALayers, but it doesn&#39;t work with CATextLayers. Any ideas?

Removing all CALayer&#39;s sublayers

I have an endlessly looping `CABasicAnimation` of a repeating image tile in my view: 

    a = [CABasicAnimation animationWithKeyPath:@&quot;position&quot;];
    a.timingFunction = [CAMediaTimingFunction 
                          functionWithName:kCAMediaTimingFunctionLinear];
    a.fromValue = [NSValue valueWithCGPoint:CGPointMake(0, 0)];
    a.toValue = [NSValue valueWithCGPoint:CGPointMake(image.size.width, 0)];
    a.repeatCount = HUGE_VALF;
    a.duration = 15.0;
    [a retain];


I have tried to &quot;pause and resume&quot; the layer animation as described in [Technical Q&amp;A QA1673](http://developer.apple.com/library/ios/#qa/qa1673/_index.html). 

When the app enters background, the animation gets removed from the layer. 
To compensate I listen to `UIApplicationDidEnterBackgroundNotification` and call `stopAnimation` and in response to `UIApplicationWillEnterForegroundNotification` call `startAnimation`.

    - (void)startAnimation 
    {
        if ([[self.layer animationKeys] count] == 0)
            [self.layer addAnimation:a forKey:@&quot;position&quot;];
        
        CFTimeInterval pausedTime = [self.layer timeOffset];
        self.layer.speed = 1.0;
        self.layer.timeOffset = 0.0;
        self.layer.beginTime = 0.0;
        CFTimeInterval timeSincePause = 
          [self.layer convertTime:CACurrentMediaTime() fromLayer:nil] - pausedTime;
        self.layer.beginTime = timeSincePause;
    }
    
    - (void)stopAnimation 
    {
        CFTimeInterval pausedTime = 
          [self.layer convertTime:CACurrentMediaTime() fromLayer:nil];
        self.layer.speed = 0.0;
        self.layer.timeOffset = pausedTime;    
    }

The problem is that it starts again at the beginning and there is ugly jump from last position, as seen on app snapshot the system took when application did enter background, back to the start of the animation loop.

I can not figure out how to make it start at last position, when I re-add the animation. Frankly, I just don&#39;t understand how that code from QA1673 works: in `resumeLayer` it sets the layer.beginTime twice, which seems redundant. But when I&#39;ve removed the first set-to-zero, it did not resume the animation where it was paused. This was tested with simple tap gesture recognizer, that did toggle the animation - this is not strictly related to my issues with restoring from background.

What state should I remember before the animation gets removed and how do I restore the animation from that state, when I re-add it later?

Restoring animation where it left off when app resumes from background 

Here is some code I struggle with for a while.

If you start the fade in animation, the label text fades in.
If I start the fade out animation the the label text fades out.

When I start the `startFade` method, only fade out is shown. How can I wait for the `fadeIn` method to finish visually before starting the `fadeOut` method.

    -(IBAction)startFade:(id)sender{
        [self fadeIn];
        [self fadeOut];
    }

    -(IBAction)fadeIn:(id)sender{
        [self fadeIn];
    }

    -(IBAction)fadeOut:(id)sender{
    [self fadeOut];
    }

    -(void) fadeIn{
        [_label setAlpha:0];
        [UILabel beginAnimations:NULL context:nil];
        [UILabel setAnimationDuration:2.0];
        [_label setAlpha:1];
        [UILabel commitAnimations];
    }

    -(void) fadeOut{
        [UILabel beginAnimations:NULL context:nil];
        [UILabel setAnimationDuration:2.0];
        [_label setAlpha:0];
        [UILabel commitAnimations];
    }

Fade In Fade Out Animation

I am using `CABasicAnimation` to move and resize an image view. I want the image view to be added to the superview, animate, and then be removed from the superview.

In order to achieve that I am listening for delegate call of my `CAAnimationGroup`, and as soon as it gets called I remove the image view from the superview.

The problem is that sometimes the image blinks in the initial location before being removed from the superview. What&#39;s the best way to avoid this behavior?

    CAAnimationGroup *animGroup = [CAAnimationGroup animation];
    	animGroup.animations = [NSArray arrayWithObjects:moveAnim, scaleAnim, opacityAnim, nil];
    	animGroup.duration = .5;
    	animGroup.delegate = self;
    	[imageView.layer addAnimation:animGroup forKey:nil];


Objective-C - CABasicAnimation applying changes after animation?

I have a `CABasicAnimation` and want to start it after a delay. In UIKit I can specify delays. The `CAMediaTiming` protocol has a `timeOffset` property but I can&#39;t see an effect. My next try is to use GCD to delay it but it feels like overkill.

How to delay a CABasicAnimation?

Is there any way to tell if a UIView is in the middle of an animation?  When I print out the view object while it is moving I notice that there is an &quot;animations&quot; entry:

    search bar should end editing: &lt;UISearchBar: 0x2e6240; frame = (0 0; 320 88); text = &#39;&#39;; autoresize = W+BM; animations = { position=&lt;CABasicAnimation: 0x6a69c40&gt;; bounds=&lt;CABasicAnimation: 0x6a6d4d0&gt;; }; layer = &lt;CALayer: 0x2e6e00&gt;&gt;

When the animation has stopped and I print the view, the &quot;animations&quot; entry is now gone:

    search bar should end editing: &lt;UISearchBar: 0x2e6240; frame = (0 0; 320 88); text = &#39;&#39;; autoresize = W+BM; layer = &lt;CALayer: 0x2e6e00&gt;&gt;

Test whether a UIView is in the middle of animation

I am trying to implement a game using the iPhone OS 4.0 (iOS4?) SDK. In the previous versions of the SDK, I&#39;ve been using the [UIView beginAnimations:context:] and [UIView commitAnimations] to create some animations. However, when I look at the documentation of the functions in 4.0, I see this comment.

&gt; Use of this method is discouraged in
&gt; iPhone OS 4.0 and later. You should
&gt; use the block-based animation methods
&gt; instead.

You can find it here:
http://developer.apple.com/iphone/library/documentation/uikit/reference/UIView_Class/UIView/UIView.html#//apple_ref/occ/clm/UIView/commitAnimations

My question is, what are block-based animations in iPhone OS 4.0? I though that the beginAnimations:context: and commitAnimations functions were used to create animation blocks..

What are block-based animation methods in iPhone OS 4.0?

I have a basic spinning animation of the iPhone. Is there any way that I can &quot;pause&quot; the animation so that the position of the view will be maintained? I guess one way of doing this would be to cause the animation to &quot;complete&quot; instead of calling &quot;remove&quot; on it, how would I do that?

    CABasicAnimation* rotationAnimation;
    rotationAnimation = [CABasicAnimation animationWithKeyPath:@&quot;transform.rotation.z&quot;];
    rotationAnimation.toValue = [NSNumber numberWithFloat: M_PI * 2];
    rotationAnimation.duration = 100;
    rotationAnimation.cumulative = YES;
    rotationAnimation.repeatCount = HUGE_VALF;
    rotationAnimation.removedOnCompletion = NO;
    rotationAnimation.fillMode = kCAFillModeForwards;
    [myView.layer addAnimation:rotationAnimation forKey:@&quot;rotationAnimation&quot;];

Is there a way to pause a CABasicAnimation?

so--i switched on &quot;color misaligned images&quot; to improve drawing performance in our app. The documentation states: 

&gt; Puts a magenta overlay over images
&gt; whose source pixels aren&#39;t aligned to
&gt; destination pixels

I don&#39;t know what the yellow means however. (There is a &quot;Color Offscreen-Rendered&quot; option that uses yellow... does &quot;Color Misaligned Images&quot; also turn on this option?)

Anybody know?

TIA

What does yellow tinting represent when using &quot;color misaligned images&quot; on iPhone/iOS

I wish to create an animation. The best way I can explain this is if you can imagine drawing a circle. It starts at the top or 12 o clock and draws clockwise all the way around until it becomes a complete circle over the space of 10 or so seconds.

The closet I have come to this is to draw a point rotating around a center point using Core Animation (using the sample code [here][1]). But I am at a loss on how to draw the circle? Any suggestions are very welcome.

Many Thanks :)

  [1]: http://nachbaur.com/blog/core-animation-part-1

iPhone Core Animation - Drawing a Circle

I want to add a view under my tab bar analog in iOS and then show it with animation coming from behind it. But when I use my code, the view that must come from behind my tab bar  overlaps my tab bar for a while. 

![tab bar and a view that shows when tab bar button pressed][1]


  [1]: http://i.stack.imgur.com/72HWj.png

This is my code: 

    - (void)handlePressedButton {
    if (pressedButton.selected) {
        [UIView beginAnimations:nil context:nil];
        [UIView setAnimationDuration:0.5];
        CGAffineTransform transform1 = CGAffineTransformMakeTranslation(-196.0, 0.0);
        CGAffineTransform transform2 = CGAffineTransformMakeTranslation(0.0, 0.0);
        [leftPanelView setTransform:transform1];
        [movedView setTransform:transform2];
        [UIView commitAnimations];
        pressedButton.selected = NO;
    }
    else {
        pressedButton.selected = YES;
        if (leftPanelView) {
            [leftPanelView removeFromSuperview];
            leftPanelView = nil;
        }
        CGRect viewFrame = CGRectMake(-196, 0, 236, 748);
        leftPanelView = [[UIView alloc] initWithFrame:viewFrame];
        leftPanelView.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:@&quot;left-nav-content.png&quot;]];
        
        // Code to populate leftPanelView according to what button is pressed.
        [self populateLeftPanelView];
        
        [UIView beginAnimations:nil context:nil];
        [UIView setAnimationDuration:0.5];
        [self.view addSubview:leftPanelView];
        CGAffineTransform transform1 = CGAffineTransformMakeTranslation(236.0, 0.0);
        CGAffineTransform transform2 = CGAffineTransformMakeTranslation(112.0, 0.0);
        [leftPanelView setTransform:transform1];
        [movedView setTransform:transform2];
        [UIView commitAnimations];
    }
}

Here the leftPanelView is the view that must come under a tab bar. Moved view is another view, that is at the right of left panel (don&#39;t mind it)

How to add a view behind other view in iOS

I&#39;m currently implementing a `CABasicAnimation` that animates a `CALayer` `transform` property.
Now, although I&#39;m new to Core Animation, I have been able to gather through various blogs and articles such as objc.io that it is a very bad idea to use the often (incorrectly) recommended method for getting animations to stick using the `fillMode` and `removedOnCompletion` properties of an animation. This method is considered bad practice by many because it creates a discrepancy between the model layer and the presentation layer, and so future queries to one of those layers may not match up with what the user is seeing.

Instead, the recommended way of doing animations is to update the model layer at the same time you add the animation to the layer being animated. However, I&#39;m having trouble understanding exactly how this is working. My animation is simple, and goes like this:

    CATransform3D updatedTransform = [self newTransformWithCurrentTransform];
    // Location 1
    CABasicAnimation *transformAnimation = [CABasicAnimation animationWithKeyPath:@&quot;transform&quot;];
    transformAnimation.duration = 1;
    transformAnimation.fromValue = [NSValue valueWithCATransform3D:self.layerBeingAnimated.transform]; // Does not work without this.
    transformAnimation.toValue = [NSValue valueWithCATransform3D:updatedTransform];
    // Location 2
    [self.layerBeingAnimated addAnimation:transformAnimation forKey:kTransformAnimationKey];
    // Location 3

I&#39;ve denoted three locations where I have attempted to update the model layer using the code
         
    self.layerBeingAnimated.transform = updatedTransform;

In location 1, the layer jumps right to `newTransform` and does not animate.
In location 2, the layer animates exactly as I want it to from the current transform to `newTransform`.
In location 3, the layer jumps right to `newTransform`, jumps back to the the old transform, animates correctly from the fromValue to newTransform, and then stays at `newTransform`.

What&#39;s the deal here? What&#39;s the correct location to update the model layer and why are these three locations producing such different results?

Thanks!

All Core Animation Solutions on Gang of Coders

Total of 35 Core Animation Solutions