Change cornerRadius using Core Animation

Question

I am trying to change the radius of the corner of a button (OpenNoteVisible.layer) as follows:

CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"cornerRadius"]; animation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear]; animation.fromValue = [NSNumber numberWithFloat:10.0f]; animation.toValue = [NSNumber numberWithFloat:0.0f]; animation.duration = 1.0; [animation.layer setCornerRadius:140.0]; [OpenNoteVisible.layer addAnimation:animation forKey:@"cornerRadius"]; 

But this code gives an error in the line [animation.layer setCornerRadius: 140.0]; I do not understand why. I imported the Quartz core framework.

Answer 1

You set the radius of the corner in the layer property of the animation object; This animation object does not have layer properties.

You need to set the radius of the corner on the layer of what you are animating, in this case OpenNoteVisible . You also need to make sure that the toValue of the animation object matches the value you set on this layer, otherwise you will get odd animations.

Your code should now be:

 CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"cornerRadius"]; animation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear]; animation.fromValue = [NSNumber numberWithFloat:10.0f]; animation.toValue = [NSNumber numberWithFloat:140.0f]; animation.duration = 1.0; [OpenNoteVisible.layer setCornerRadius:140.0]; [OpenNoteVisible.layer addAnimation:animation forKey:@"cornerRadius"]; 

Answer 2

Swift 4 solution is below

 import UIKit import PlaygroundSupport let view = UIView(frame: CGRect(x: 0, y: 0, width: 400, height: 400)) view.backgroundColor = #colorLiteral(red: 1, green: 0.5763723254, blue: 0, alpha: 1) PlaygroundPage.current.liveView = view UIView.animate(withDuration: 2.5, animations: { view.layer.cornerRadius = 40 }, completion: { _ in UIView.animate(withDuration: 0.5, animations: { view.layer.cornerRadius = 0 }) })