Shouldn&#39;t you be using the `[CAMediaTiming beginTime]` property ([reference][1])?

See *Customizing the Timing of an Animation* in the [Core Animation Programming Guide][2].


    CABasicAnimation *animation;
    animation.beginTime = CACurrentMediaTime() + 0.3; //0.3 seconds delay

  [1]: https://developer.apple.com/documentation/quartzcore/camediatiming/1427654-begintime
  [2]: https://developer.apple.com/library/archive/documentation/Cocoa/Conceptual/CoreAnimation_guide/AdvancedAnimationTricks/AdvancedAnimationTricks.html

In Swift 3.0:

    func animateYourView () {
       let myDelay = 5.0
       let scalePulseAnimation: CABasicAnimation = CABasicAnimation(keyPath: &quot;transform.scale&quot;)
       scalePulseAnimation.beginTime = CACurrentMediaTime() + myDelay
       scalePulseAnimation.duration = 0.5
       scalePulseAnimation.repeatCount = 2.0
       scalePulseAnimation.autoreverses = true
       scalePulseAnimation.fromValue = 1.0
       scalePulseAnimation.toValue = 0.5
       myView.layer.add(scalePulseAnimation, forKey: &quot;scale&quot;)
    }

Where the key line for the delay is:

      scalePulseAnimation.beginTime = CACurrentMediaTime() + myDelay


I want to plot a label that looks like this in `ggplot2`:

`Value is $\sigma$, R^{2} = 0.6` where `Value is` is ordinary font, `$\sigma$` is a Greek lowercase sigma letter and `R^{2} = 0.6` appears as an `R` with a superscript `2` followed by equal sign (`=`) followed by `0.6`. How can this be used in ggplot `factor`s and in arguments to things like `xlab,ylab` of R?

Putting mathematical symbols and subscripts mixed with regular letters

What benefits arise from naming a function&#39;s return parameter(s)?

    func namedReturn(i int) (ret int) {
        ret = i
        i += 2
        return
    }

    func anonReturn(i int) int {
        ret := i
        i += 2
        return ret
    }

Why would return parameters be named?

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?

<p>I have a <code>CABasicAnimation</code> and want to start it after a delay. In UIKit I can specify delays. The <code>CAMediaTiming</code> protocol has a <code>timeOffset</code> property but I can't see an effect. My next try is to use GCD to delay it but it feels like overkill.</p>


What is exact difference between &#39;YYYY&#39; and &#39;yyyy&#39;. I read in [this link][1], it states that 

&gt; A common mistake is to use YYYY. yyyy specifies the calendar year
&gt; whereas YYYY specifies the year (of “Week of Year”), used in the ISO
&gt; year-week calendar. In most cases, yyyy and YYYY yield the same
&gt; number, however they may be different. Typically you should use the
&gt; calendar year.

But when I try to use 

    NSString *stringDate = @&quot;Feb 28, 2013 05:30pm&quot;;
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    [dateFormatter setDateFormat:@&quot;MMM dd, yyyy hh:mma&quot;];
    NSDate *date=[dateFormatter dateFromString:stringDate];
    NSLog(@&quot;Date 1 : %@&quot;,date); //2013-02-28 12:00:00 +0000
    
    NSString *stringDatee = @&quot;Feb 28, 2013 05:30pm&quot;;
    NSDateFormatter *dateFormatterr = [[NSDateFormatter alloc] init];
    [dateFormatterr setDateFormat:@&quot;MMM dd, YYYY hh:mma&quot;];
    NSDate *datee=[dateFormatterr dateFromString:stringDatee];
    NSLog(@&quot;Date 2 : %@&quot;,datee); //2013-01-05 12:00:00 +0000
    
    NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init];
    [dateFormat setDateFormat:@&quot;MMM dd, YYYY hh:mma&quot;];
    NSString *dateString = [dateFormat stringFromDate:datee];
    NSLog(@&quot;date 3 : %@&quot;, dateString); //Jan 05, 2013 05:30PM

As here, result to `date` and `datee` different, which I understood, but why result of date 2 and date 3 are different? As I am creating date from string and reversing same to string again, but output mismatches?

Has anybody knows reason about same?. Though it specifies week of year, still I should get result same.

Thanks..

EDIT :-

If I code

    NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init];
    [dateFormat setDateFormat:@&quot;MMM dd, YYYY hh:mma&quot;];
    NSString *dateString = [dateFormatterr stringFromDate:[NSDate date]];
    NSLog(@&quot;date: %@&quot;, dateString); //Feb 28, 2013 04:37PM

If results me proper result, but same which I pass as string to date I get `2013-01-05 12:00:00 +0000`, check date 2 of NSLog, Strange result, why?

  [1]: https://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/DataFormatting/Articles/dfDateFormatting10_4.html#//apple_ref/doc/uid/TP40002369-SW1

Difference between &#39;YYYY&#39; and &#39;yyyy&#39; in NSDateFormatter

I am currently trying to track the states of a textfield.

I am using a custom datePicker which sets the text via `-setText` 

    [self.textField setText:[self.dateFormatter stringFromDate:self.date]];

Inside my *textFieldDelegate* I wrote the following code:

    -(void)viewDidLoad {
      [super viewDidLoad];
      self.travelToOnTextField.delegate = self;
      [self.travelToOnTextField addTarget:self action:@selector(travelToOnTextFieldDidChange:) forControlEvents:UIControlEventEditingChanged];
    }
        
    -(void)travelToOnTextFieldDidChange:(id)sender
    {
       NSLog(@&quot;Event Handler called&quot;);
    }

If I change the text through my custom Datepicker the Method `travelToOnDateTextFieldDidChange` doesn&#39;t get called. But if I change the text using my Computer Keyboard it gets called for some reason. 

Is this intentional?

UIControlEventEditingChanged doesn&#39;t get fired when using setText of UITextfield

How can I check if location service is enabled for my app?

I have 2 storyboards and I want to check location service. If location service enabled for my app, I want to launch map storyboard with location. Otherwise, I want to launch another storyboard. How can I do programmatically?

Checking location service permission on iOS

I can&#39;t find a way to create a &#39;square&#39; constraint, meaning &#39;width equals height&#39; in Interface Builder. I guess it&#39;s possible to add such constraint programmatically. Is there something I can do in IB? Maybe I just don&#39;t see it? It seems trivial, yet I can&#39;t find it.

&quot;Width equals height&quot; constraint in Interface Builder

If a add a border of a view using code in a view like

    self.layer.borderColor = [UIColor yellowColor].CGColor;
    self.layer.borderWidth = 2.0f;
the border is added inside the view like the following:
![enter image description here][1]


the right view is the original view, as you can see, the black area of bordered view is less than the original one. but what I want to get is a border outside of original view, like this:![enter image description here][2]. the black area is equal to original one, how can I  implement it?


  [1]: http://i.stack.imgur.com/bhbts.png
  [2]: http://i.stack.imgur.com/yZj7C.png

Add a border outside of a UIView (instead of inside)

I have a `UIViewController`. How do I draw a line in one of its programmatically created views?


How do you draw a line programmatically from a view controller?

I know how to change the height of the section headers in the table view.  But I am unable to find any solution to change the default spacing before the first section.

Right now I have this code:

    - (CGFloat)tableView:(UITableView *)tableView heightForHeaderInSection:(NSInteger)section{
        if (section == 0){
            return 0;
        }
        return 10;
    }

![enter image description here][1]


  [1]: http://i.stack.imgur.com/Q7n3F.png



How to change height of grouped UITableView header?

I have encountered something a bit strange with contentInsets

I have a UITextView in my storyboard with a contentInset of 50 left, as I&#39;m trying to add some padding to my uitextview 

However, a scrollbar appears on the bottom of the uitextview, as shown below in this test:![enter image description here][1]

  [1]: http://i.stack.imgur.com/uAIdL.png

I was under the impression that contentInset squashes the uitextview without causing this horizontal scroll bar, so how can I remove the need for the horizontal scrollbar and make everything--the inset AND all the text in the uitextview--visible without the need for this scrollbar.

N.B: I&#39;m not asking about preventing the scrolling horizontally or not displaying the scrollbar(thus cutting of the text)

Thanks a lot!

For atomk(UITextView is called ss)

    NSLog(@&quot;Content Size Before %f&quot;,self.ss.contentSize.width); Logs: 280
    CGSize size=self.ss.contentSize; size.width=size.width-50;
    [self.ss setContentSize:size]; 
    NSLog(@&quot;Content Size After %f&quot;,self.ss.contentSize.width); Logs: 230

There is **no** visible difference between the view with the code added than before it was added, so something&#39;s going wrong!
(Thanks)

UITextView content inset

---

**iOS 7.1 UPDATE**: Looks like the workaround for modifying the alpha channel in the UINavigationBar has been ignored in this update. Right now, the best solution seems to be to just &#39;deal with it&#39; and hope that whatever color you choose can render a translucent effect. I am still looking into ways of getting around this.

--- 

**iOS 7.0.3 UPDATE**: The [GitHub library we created](https://github.com/croberts22/CRNavigationController) has been updated to slightly work around this issue when using iOS 7.0.3. Unfortunately, there is no magic formula to support both colors created in iOS 7.0.2 and earlier and iOS 7.0.3. Seems like Apple improved the saturation, but at the cost of opacity (since the blurred translucency is dependant on the opacity level). I, along with a few others, are working on creating a much better fix for this.

---

I&#39;m sure many people have already come across the problem where iOS 7 tends to desaturate the color of a UINavigationBar that is translucent.

My goal is to achieve a UINavigationBar with this tint color, but translucent:

![UINavigationBar, Opaque][1]


However, with translucency, I&#39;m getting this. The background view is white, which I understand will make this view a bit lighter:

![UINavigationBar, Translucent][2]

Is there any way to achieve the original color while still having translucency? I&#39;ve noticed Facebook has been able to get their bar to be their rich, blue color, as displayed here:

![Facebook UINavigationBar, Translucent][3]

..so I know there has to be some way. Background views obviously make a difference here, but most of their content is also gray/white. It seems that regardless of whatever bar tint color you put in, you are unable to get vivid colors under translucency.

**Updated with solution.**

Here&#39;s the solution that I ended up coming up with. I took [aprato](https://stackoverflow.com/a/18906759/692051)&#39;s solution and then encompassed the custom `UINavigationBar` within a `UINavigationController` subclass. [I have created a repository that has this implementation listed below, along with an example app](https://github.com/croberts22/CRNavigationController). 


    ////////////////////////////
    // CRNavigationBar.m
    ////////////////////////////
 
    #import &quot;CRNavigationBar.h&quot;
 
    @interface CRNavigationBar ()
    @property (nonatomic, strong) CALayer *colorLayer;
    @end
 
    @implementation CRNavigationBar
 
    static CGFloat const kDefaultColorLayerOpacity = 0.5f;
    static CGFloat const kSpaceToCoverStatusBars = 20.0f;
 
    - (void)setBarTintColor:(UIColor *)barTintColor {
        [super setBarTintColor:barTintColor];
        if (self.colorLayer == nil) {
            self.colorLayer = [CALayer layer];
            self.colorLayer.opacity = kDefaultColorLayerOpacity;
            [self.layer addSublayer:self.colorLayer];
        }
        self.colorLayer.backgroundColor = barTintColor.CGColor;
    }
 
    - (void)layoutSubviews {
        [super layoutSubviews];
        if (self.colorLayer != nil) {
            self.colorLayer.frame = CGRectMake(0, 0 - kSpaceToCoverStatusBars, CGRectGetWidth(self.bounds), CGRectGetHeight(self.bounds) + kSpaceToCoverStatusBars);
        
            [self.layer insertSublayer:self.colorLayer atIndex:1];
        }
    }
 
    @end

---

    ////////////////////////////
    // CRNavigationController.m
    ////////////////////////////
 
    #import &quot;CRNavigationController.h&quot;
    #import &quot;CRNavigationBar.h&quot;
 
    @interface CRNavigationController ()
 
    @end
 
    @implementation CRNavigationController
 
    - (id)init {
        self = [super initWithNavigationBarClass:[CRNavigationBar class] toolbarClass:nil];
        if(self) {
            // Custom initialization here, if needed.    
        }
        return self;
    }
 
    - (id)initWithRootViewController:(UIViewController *)rootViewController {
        self = [super initWithNavigationBarClass:[CRNavigationBar class] toolbarClass:nil];
        if(self) {
            self.viewControllers = @[rootViewController];
        }
    
        return self;
    }
 
    @end

  [1]: http://i.stack.imgur.com/9RjRa.png
  [2]: http://i.stack.imgur.com/RA5wt.png
  [3]: http://i.stack.imgur.com/C5jXs.png

Achieving bright, vivid colors for an iOS 7 translucent UINavigationBar

I have some strange issue with `UITableView` only in iOS 7.

`UITableViewCellSeparator` disappears above the first row and below the last row. Sometimes after selecting the rows or some scrolling actions it appears.

In my case `tableView` is loaded from the `Storyboard` with `UITableViewStylePlain` style. The problem is surely not in `UITableViewCellSeparatorStyle`, which is not changed from default `UITableViewCellSeparatorStyleSingleLine`.

As I read at ***Apple Dev Forums*** (*[here][1] and [here][2]*) other people have such problem and some workarounds are found, for example:

    Workaround: disable the default selection and recreate the behaviour in a method
    trigged by a tapGestureRecognizer.

But I am still searching for the reason of such separator strange behaviour.

Any ideas?


**Update:** As I saw in XCode 5.1 DP and iOS 7.1 beta, Apple tried to fix this problem. Now separator is shown as needed sometimes below the last row, after some refreshing, but not after tableview creation.

  [1]: https://devforums.apple.com/message/889468#889468
  [2]: https://devforums.apple.com/message/885634#885634

UITableViewCell Separator disappearing in iOS7

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

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&#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!

CABasicAnimation does not animate correctly when I update model layer

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.

Content Type	Original Author	Original Content on Stackoverflow
Question	openfrog	View Question on Stackoverflow
Solution 1 - Ios	trojanfoe	View Answer on Stackoverflow
Solution 2 - Ios	Dave G	View Answer on Stackoverflow

How to delay a CABasicAnimation?

Ios Problem Overview

Ios Solutions

Solution 1 - Ios

Solution 2 - Ios

Why would return parameters be named?

Putting mathematical symbols and subscripts mixed with regular letters

Attributions