Auto Layout constraint on CALayer IOS

Hi I am developing iPhone application in which I tried to set one side border for edittext. I did this in following way:

 int borderWidth = 1;
CALayer *leftBorder = [CALayer layer];

leftBorder.borderColor = [UIColor whiteColor].CGColor;
leftBorder.borderWidth = borderWidth;

leftBorder.frame = CGRectMake(0, textField.frame.size.height - borderWidth, textField
                              .frame.size.width, borderWidth);
[textField.layer addSublayer:leftBorder];

I put some constraints on my edittext in IB so that when I rotate my device it will adjust width of text field according to that. My problem is that adjusts the width of edittext not adjusting the width of CALayer which I set for my edit text. So I think I have to put some constraints for my CALayer item as well. But I dont know how to do that. ANy one knows about this? Need Help. Thank you.

Solution 1:

the whole autoresizing business is view-specific. layers don't autoresize.

what you have to do -- in code -- is to resize the layer yourself

e.g.

in a viewController you would do

- (void) viewDidLayoutSubviews {
  [super viewDidLayoutSubviews]; //if you want superclass's behaviour... 
  // resize your layers based on the view's new frame
  self.editViewBorderLayer.frame = self.editView.bounds;
}

or in a custom UIView you could use

- (void)layoutSubviews {
  [super layoutSubviews]; //if you want superclass's behaviour...  (and lay outing of children)
  // resize your layers based on the view's new frame
  layer.frame = self.bounds;
}

Solution 2:

In Swift 5, you can try the following solution:

Use KVO, for the path "YourView.bounds" as given below.

self.addObserver(self, forKeyPath: "YourView.bounds", options: .new, context: nil)

Then handle it as given below.

override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
        if keyPath == "YourView.bounds" {
            YourLayer.frame = YourView.bounds
            return
        }
        super.observeValue(forKeyPath: keyPath, of: object, change: change, context: context)
    }

More info about this here

Solution 3:

According to this answer, layoutSubviews does not get called in all needed cases. I have found this delegate method more effective:

- (instancetype)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if(self != nil) {
        [self.layer addSublayer:self.mySublayer];
    }
    return self;
}

- (void)layoutSublayersOfLayer:(CALayer*)layer
{
    self.mySublayer.frame = self.bounds;
}