How to animate layer shadowOpacity?

Question

This will work properly:

#import <QuartzCore/CAAnimation.h>

CABasicAnimation *anim = [CABasicAnimation animationWithKeyPath:@"shadowOpacity"];
anim.fromValue = [NSNumber numberWithFloat:1.0];
anim.toValue = [NSNumber numberWithFloat:0.0];
anim.duration = 1.0;
[vv.layer addAnimation:anim forKey:@"shadowOpacity"];
vv.layer.shadowOpacity = 0.0;

For Swift 3.0:

 let animation = CABasicAnimation(keyPath: "shadowOpacity")
 animation.fromValue = layer.shadowOpacity
 animation.toValue = 0.0
 animation.duration = 1.0
 view.layer.add(animation, forKey: animation.keyPath)
 view.layer.shadowOpacity = 0.0

I've put above code in a little extension of UIView:

extension UIView {

func animateLayer<Value>(_ keyPath: WritableKeyPath<CALayer, Value>, to value:Value, duration: CFTimeInterval) {

    let keyString = NSExpression(forKeyPath: keyPath).keyPath
    let animation = CABasicAnimation(keyPath: keyString)
    animation.fromValue = self.layer[keyPath: keyPath]
    animation.toValue = value
    animation.duration = duration
    self.layer.add(animation, forKey: animation.keyPath)
    var thelayer = layer
    thelayer[keyPath: keyPath] = value
}
}

Usage like:

animateLayer(\.shadowOffset, to: CGSize(width: 3, height: 3), duration:1)
animateLayer(\.shadowOpacity, to: 0.4, duration: 1)

It's not thoroughly tested. but worked for me. (Also posted here)

The below code work for me

1)Add QuartzCore frame work 2)Import QuartzCore frame work

Add the following Code in the required place

UIImageView * glowimageview = [[[UIImageView alloc]init]autorelease];
    [glowimageview setFrame:CGRectMake(500,400,200,200)];
    [glowimageview setImage:[UIImage imageNamed:@"144.png"]];
    [sender addSubview:glowimageview];

    glowimageview.layer.shadowColor = [UIColor redColor].CGColor;
    glowimageview.layer.shadowRadius = 10.0f;
    glowimageview.layer.shadowOpacity = 1.0f;
    glowimageview.layer.shadowOffset = CGSizeZero;

    CABasicAnimation *shadowAnimation = [CABasicAnimation animationWithKeyPath:@"shadowOpacity"];
    shadowAnimation.duration=1.0;
    shadowAnimation.repeatCount=HUGE_VALF;
    shadowAnimation.autoreverses=YES;
    shadowAnimation.fromValue = [NSNumber numberWithFloat:1.0];
    shadowAnimation.toValue = [NSNumber numberWithFloat:0.0];
    [glowimageview.layer addAnimation:shadowAnimation forKey:@"shadowOpacity"];

It will works. Change the format of the code as per your requirement

Here's a material design like take on some of the above with animations It's also available here as framework through Carthage https://github.com/sevenapps/SVNMaterialButton

public init(frame: CGRect, color: UIColor) {
    super.init(frame: frame)
    self.backgroundColor = color
    self.layer.masksToBounds = false
    self.layer.borderWidth = 1.0
    self.layer.shadowColor = UIColor.black.cgColor
    self.layer.shadowOpacity = 0.8
    self.layer.shadowRadius = 8
    self.layer.shadowOffset = CGSize(width: 8.0, height: 8.0)
}

required public init?(coder aDecoder: NSCoder) {
    fatalError("This class is not set up to be instaciated with coder use init(frame) instead")
}

public override func layoutSubviews() {
    super.layoutSubviews()
    self.layer.cornerRadius = self.frame.height / 4
}

public override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
    self.animate(to: 0.5, and: CGSize(width: 5.0, height: 5.0), with: 0.5)
    super.touchesBegan(touches, with: event)
}

public override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
    self.animate(to: 0.8, and: CGSize(width: 8.0, height: 8.0), with: 0.5)
    super.touchesBegan(touches, with: event)
}

private func animate(to opacity: Double, and offset: CGSize, with duration: Double){
    CATransaction.begin()
    let opacityAnimation = CABasicAnimation(keyPath: "shadowOpacity")
    opacityAnimation.toValue = opacity
    opacityAnimation.duration = duration
    opacityAnimation.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseOut)
    opacityAnimation.fillMode = kCAFillModeBoth
    opacityAnimation.isRemovedOnCompletion = false

    let offsetAnimation = CABasicAnimation(keyPath: "shadowOffset")
    offsetAnimation.toValue = offset
    offsetAnimation.duration = duration
    offsetAnimation.timingFunction = opacityAnimation.timingFunction
    offsetAnimation.fillMode = opacityAnimation.fillMode
    offsetAnimation.isRemovedOnCompletion = false

    self.layer.add(offsetAnimation, forKey: offsetAnimation.keyPath!)
    self.layer.add(opacityAnimation, forKey: opacityAnimation.keyPath!)
    CATransaction.commit()
}