In WWDC 2012 Polishing Your Interface Rotations video (sadly, no longer available online) they talked about the advantages and implications of rasterizing layers.

Bottom line if you have a complex view (i.e. relatively expensive to re-render) that you are animating, but for which the animated view is not itself changing, rasterizing the layer can improve the performance by not re-rendering the layer all the time. But it does this at the cost of memory (saving a rasterized image in memory).

But, if you animate a change within the layer, the `shouldRasterize` can adversely affect performance (because it&#39;s going to re-rasterize the layer for each frame of the animation).

Generally, if animating a complex set of layers that, themselves, are not changing, then you can set `shouldRasterize` to `YES`, do the animation, and then turn off `shouldRasterize`.


  [1]: https://developer.apple.com/videos/wwdc/2012/?id=240

I know I can use the following 2 commands to download a file:

    curl -O example.com/file.zip
    wget example.com/file.zip

But I want them to go into a specific directory. So I can do the following:

    curl -o mydir/file.zip example.com/file.zip
    wget -O mydir/file.zip example.com/file.zip

Is there a way to not have to specify the filename? Something like this:

    curl -dir mydir example.com/file.zip



How to download a file into a directory using curl or wget?

Is there any plugin or library which I need to use for this?
I want to try this on my local system first and then do the same on Heroku Postgresql

How should I import data from CSV into a Postgres table using pgAdmin 3?

I&#39;ve seen fixes for some lagyness issues by setting the layer property of the view

    view.layer.shouldRasterize = YES;

I saw a great difference in performance when using a UICollectionView and preparing the cells and setting the propery.

Not sure what the implications are.

Would be great to get an explanation.
Thanks!





When should I set layer.shouldRasterize to YES

I've seen fixes for some lagyness issues by setting the layer property of the view
<pre><code class="hljs language-ini">view.layer.shouldRasterize = YES;
</code></pre>
I saw a great difference in performance when using a UICollectionView and preparing the cells and setting the propery.
Not sure what the implications are.
Would be great to get an explanation.
Thanks!

For a given `NSRange`, I&#39;d like to find a `CGRect` in a `UILabel` that corresponds to the glyphs of that `NSRange`. For example, I&#39;d like to find the `CGRect` that contains the word &quot;dog&quot; in the sentence &quot;The quick brown fox jumps over the lazy dog.&quot;

![Visual description of problem][1]

The trick is, the `UILabel` has multiple lines, and the text is really `attributedText`, so it&#39;s a bit tough to find the exact position of the string.

The method that I&#39;d like to write on my `UILabel` subclass would look something like this:

     - (CGRect)rectForSubstringWithRange:(NSRange)range;

-----
*Details, for those who are interested:*

My goal with this is to be able to *create a new UILabel with the exact appearance and position of the UILabel, that I can then animate.* I&#39;ve got the rest figured out, but it&#39;s this step in particular that&#39;s holding me back at the moment.


**What I&#39;ve done to try and solve the issue so far:**

 - I&#39;d hoped that with iOS 7, there&#39;d be a bit of Text Kit that would solve this problem, but most every example I&#39;ve seen with Text Kit focuses on `UITextView` and `UITextField`, rather than `UILabel`.
 - I&#39;ve seen another question on Stack Overflow here that promises to solve the problem, but the accepted answer is over two years old, and the code doesn&#39;t perform well with attributed text.

**I&#39;d bet that the right answer to this involves one of the following:**

 - Using a standard Text Kit method to solve this problem in a single line of code. I&#39;d bet it would involve `NSLayoutManager` and `textContainerForGlyphAtIndex:effectiveRange`
 - Writing a complex method that breaks the UILabel into lines, and finds the rect of a glyph within a line, likely using Core Text methods. My current best bet is to take apart [@mattt&#39;s][2] excellent [TTTAttributedLabel][3], which has a method that finds a glyph at a point - if I invert that, and find the point for a glyph, that might work.

-----
Update: Here&#39;s a github gist with the three things I&#39;ve tried so far to solve this issue: https://gist.github.com/bryanjclark/7036101


  [1]: http://i.stack.imgur.com/kHGFF.png
  [2]: https://stackoverflow.com/users/157142/mattt
  [3]: https://github.com/mattt/TTTAttributedLabel

How do I locate the CGRect for a substring of text in a UILabel?

I need to create a `UILabel` with a background color, and I&#39;d like to add some left/right leading/trailing horizontal padding.

But every solution I&#39;ve found seems like a nasty hack. 

What is the &#39;standard&#39; way to achieve this from iOS 5 forward?

A screenshot to illustrate my scenario:

![left padding needed ][1]

[1]: http://i.stack.imgur.com/m5Li2.png

Add left/right horizontal padding to UILabel

I&#39;ve just started using AFNetworking 2.0 and I was wondering how I put in headers into a HTTP Get request. The documentation sets up a GET like this:

    AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];
    NSDictionary *parameters = @{@&quot;foo&quot;: @&quot;bar&quot;};
    [manager POST:@&quot;http://example.com/resources.json&quot; parameters:parameters success:^(AFHTTPRequestOperation *operation, id responseObject) {
    NSLog(@&quot;JSON: %@&quot;, responseObject);
    } failure:^(AFHTTPRequestOperation *operation, NSError *error) {
    NSLog(@&quot;Error: %@&quot;, error);
    }];

But since we&#39;re not handling `NSURLRequests` I&#39;m not sure how to set HTTP Headers.

Any help would be appreciated.
&lt;br&gt;Regards,&lt;br&gt;Mike

AFNetworking 2.0 add headers to GET request

I use `NSAttributedString` to generate a string with two different sizes. By default, its bottom alignment looks like this:

![baseline aligned sizes][1]

But I want to center it vertically, like this:
![vertically centered sizes][2]

To be clear, this is a single attributed string, not two or more. This is a simplified example to describe my question, what I&#39;d actually like to do is more complex.

  [1]: http://i.stack.imgur.com/CmMcd.png
  [2]: http://i.stack.imgur.com/jb9D6.png

Center two fonts with different different sizes vertically in an NSAttributedString

Appareantly there is no `AFImageRequestOperation`, but only `AFImageResponseSerializer` and frankly I don&#39;t get it or maybe I&#39;m just looking too long through AFNetworking site... Downloading images with previous AFNetworking was like a charm. I&#39;d hate to go back to older AFnetworking, since I did almost all stuff via the new version... Anyone?

How to download image with AFNetworking 2.0?

I know this appears to be a duplicate of some other questions, but the answers are not working for me.

 1. I have created a single view app.  
 2. In the storyboard I added a subview to my main view.  
 3. I have a label on my main view and another label on my subview.  
 4. I have created a class of type UIView and added it as the custom class for the subview.  
 5. I can ctrl-drag my label on my main view to the main view controller class.  But when I try to ctrl-drag my label on my subview to my custom class, I cannot get the connection to occur.  
 6. I have even typed the property information and tried to make the connection manually to no avail.  

Things have changed a bit in the latest version of Xcode&#39;s Interface Builder.  Can somebody tell me what I am missing?  There is literally no code here.  I am just testing trying to connect outlets to a subview with a custom class.

The first image shows that I have set up the custom class and added a property but I cannot make the connection.

![Main view and subview in Interface Builder - custom class is set][1]

The second image shows the main view label is connected in the main view&#39;s controller.

![Main view and subview in Interface Builder - main view&#39;s label is connected][2]

The third image shows that there are no outlet connections for the subview&#39;s label.

![Main view and subview in Interface Builder - cannot connect subview&#39;s label][3]


  [1]: http://i.stack.imgur.com/nFNpj.png
  [2]: http://i.stack.imgur.com/TzT2J.png
  [3]: http://i.stack.imgur.com/REDh5.png

Cannot create outlet connections to subviews in Interface Builder (Xcode 5)

I would like to know how to use the `UIView` property `clipsToBounds`.

The official documentation says the following:

&gt; `clipsToBounds` *property*
&gt; 
&gt; A Boolean value that determines whether subviews are confined to the
&gt; bounds of the view.
&gt; 
&gt; **Discussion**&lt;br/&gt;
&gt; Setting this value to `YES` causes subviews to be clipped to the
&gt; bounds of the receiver. If set to `NO`, subviews whose frames extend
&gt; beyond the visible bounds of the receiver are not clipped. The default
&gt; value is `NO`.

But I&#39;m unclear on what this means exactly.  How should I be using `clipsToBounds`?  What are the consequences of setting this property to `YES` exactly? Or to `NO`?

How does clipsToBounds work?

I have a `UIView` added in code at run time.

I want to draw a `UIBezierPath` in it, but does this means i have to override the `drawRect` for UIView?

Or is there another way of drawing to it on the custom made `UIView`?


Here is the code for generating the `UIView`:

    UIView* shapeView = [[UIView alloc]initWithFrame:CGRectMake(xOrigin,yOrigin+(i*MENU_BLOCK_FRAME_HEIGHT), self.shapeScroll.frame.size.width, MENU_BLOCK_FRAME_HEIGHT)];
    shapeView.clipsToBounds = YES;


And here is the function to create and return a `UIBezierPath`:

    - (UIBezierPath*)createPath
    {
        UIBezierPath* path = [[UIBezierPath alloc]init];
        [path moveToPoint:CGPointMake(100.0, 50.0)];
        [path addLineToPoint:CGPointMake(200.0,50.0)];
        [path addLineToPoint:CGPointMake(200.0, 200.0)];
        [path addLineToPoint:CGPointMake(100.0, 200.0)];
        [path closePath];
        return path;
    }



Drawing UIBezierPath on code generated UIView

I&#39;m trying to rotate an ``UIView`` a few radians but after applying the transformation it doesn&#39;t look to be keeping its size. What&#39;s the proper way to achieve this?

Here&#39;s what I&#39;m doing and what I get (Blue box with the arrow is the View I&#39;m trying to rotate -- it should keep same aspect as red box behind):

    #define DEGREES_TO_RADIANS(angle) ((angle) / 180.0 * M_PI)

    double rads = DEGREES_TO_RADIANS(240);
    CGAffineTransform transform = CGAffineTransformRotate(CGAffineTransformIdentity, rads);
    self.arrowView.transform = transform;

![enter image description here][1]

Thanks!


  [1]: http://i.stack.imgur.com/GGDxk.png

Rotate UIView around its center keeping its size

I have the following CATransition for a UIView called `finalScoreView`, which makes it enter the screen from the top:

    CATransition *animation = [CATransition animation];
    animation.duration = 0.2;
    animation.type = kCATransitionPush;
    animation.subtype = kCATransitionFromBottom;
    animation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseIn];
    
    [gameOver.layer addAnimation:animation forKey:@&quot;changeTextTransition&quot;];
    [finalScoreView.layer addAnimation:animation forKey:@&quot;changeTextTransition&quot;];

How do I make it so it bounces once after it comes down, then stays still?  It should still enter the screen from the top but then bounce when it comes down.

Any help would be much appreciated, thanks!

How to create a UIView bounce animation?

I want to put a UICollectionView control that shows thumbs horizontally (only a single line of thumbs). For some reason the UICollectionView push the thumbs 44 pixels down, so the &quot;0&quot; height is actually &quot;44&quot;. I assume it might be adding this space to consider the navigation bar height (I just assume). Since my UICollectionView is only on part of the screen, I don&#39;t want this margin. Is there a way to remove it?

UICollectionView adds top margin

I am attempting to update a single cell inside a `UICollectionView`, specifically I am just trying to update an image in that specific cell detonated by `cell.imageView`. `[self.collectionView reloadData]` is not really an option because it makes the whole collection view flash. `[self.collectionView beginUpdates]` is not a thing in a `UICollectionView`it seems. 

I understand I may be able to use:

    [self.collectionView performBatchUpdates:^{
        //do something
    } completion:nil];

I am not exactly sure what to put inside a completion block to update that certain cell&#39;s `imageView`. This is all being done inside of `didSelectItemAtIndexPath`.Also I am not using `NSFetchedResultsController `. Any ideas?

UICollectionView update a single cell

How do I properly resize a UICollectionView so that it fully displays its contents? I have tried many things, including setting its frame, calling ``reloadData`` and invalidating the layout:

    self.collectionView.contentSize = CGSizeMake(300, 2000);
    self.collectionView.frame = CGRectMake(0, 0, 300, 2000);
    [self.collectionView reloadData];
    [self.collectionView.collectionViewLayout invalidateLayout];

but none of this has any effect. After pressing the button I still see the initial view, like this:

![collection view only showing part of the content after frame resize][1]

I have a small demo program where I have a data source producing 100 elements. In Interface Builder I initially set the size of the UICollectionView to a small value so that not all elements fit, after that I press a button after which the code above is executed. I expect the UICollectionView to now show all elements, but it doesn&#39;t.

***EDIT:** The demo program can be found at [https://github.com/mjdemilliano/TestUICollectionView][2].*

***EDIT2:** I have observed that the frame update is lost at some point, because if I press the button again, the current frame is back to the old value. After adding some log statements in the button event handler, the log output is:*

    before: frame = {{0, 58}, {320, 331}}, contentSize = {320, 1190}
    update button pressed
    after: frame = {{0, 0}, {300, 2000}}, contentSize = {300, 2000}
    before: frame = {{0, 58}, {320, 331}}, contentSize = {320, 1190}
    update button pressed
    after: frame = {{0, 0}, {300, 2000}}, contentSize = {300, 2000}

*I don&#39;t understand why the frame change is not kept, what is changing it.*

At some point I will replace the hardcoded values by values obtained from the flow layout, but I wanted to rule that out and keep my example as simple as possible.

Context: What I want to do eventually is the following: I have a scrollable view with various controls like labels and images, and a collection view with dynamic content. I want to scroll all that, not just the collection view, therefore I am not using the collection view&#39;s own scrolling facilities, which work fine.


  [1]: http://i.stack.imgur.com/Wlzkc.png
  [2]: https://github.com/mjdemilliano/TestUICollectionView

UICollectionView autosize height

I keep getting &#39;Unable to simultaneously satisfy constraints&#39; exceptions (Xcode 5, iOS 7, both device and simulator), where one of the constraints in the list is something like this:

    &quot;&lt;NSLayoutConstraint:0x165b23d0 &#39;UIView-Encapsulated-Layout-Width&#39;
    H:[StoryPlayerCell:0x165affc0(0)]&gt;&quot;

I did not set this constraint myself. It&#39;s also not an `NSAutoresizingMaskLayoutConstraint`.
But where does it come from? And how can I get rid of it?

I have no idea.
And I can&#39;t find anything about `&#39;UIView-Encapsulated-Layout-Width&#39;` in the Apple&#39;s documentation.
Even the Google search returns nothing at all.

Any suggestions?

PS: I&#39;m using this cell in a `UICollectionView` with a custom subclass of `UICollectionViewFlowLayout`. Maybe the `&#39;Encapsulated-Layout&#39;` part has something to do with this?

What is a &#39;UIView-Encapsulated-Layout-Width&#39; constraint?

I am using a UICollectionView in my project, where there are multiple cells of differing widths on a line. According to:
https://developer.apple.com/library/content/documentation/WindowsViews/Conceptual/CollectionViewPGforIOS/UsingtheFlowLayout/UsingtheFlowLayout.html

it spreads the cells out across the line with equal padding. This happens as expected, except I want to left justify them, and hard code a padding width.

I figure I need to subclass UICollectionViewFlowLayout, however after reading some of the tutorials etc online I just don&#39;t seem to get how this works.


Content Type	Original Author	Original Content on Stackoverflow
Question	Avner Barr	View Question on Stackoverflow
Solution 1 - Ios	Rob	View Answer on Stackoverflow

When should I set layer.shouldRasterize to YES

Ios Problem Overview

Ios Solutions

Solution 1 - Ios

How should I import data from CSV into a Postgres table using pgAdmin 3?

How to download a file into a directory using curl or wget?

Attributions