[CAKeyframeAnimation setFromValue:]: unrecognized selector sent to instance - ios

Question

I'm trying to animate a button with keyframeanimate with a button that I want to modify it's tintColor and buttons width constraint that I want to scale it 2x and vise versa, here is my code
func InitialAnimationToTutorialButton() {
UIView.animateKeyframes(withDuration: 1.5, delay: 0, options: [.repeat], animations: {
UIView.addKeyframe(withRelativeStartTime: 0, relativeDuration: 0.1, animations: {
self.tutorialButton.tintColor = UIColor(rgb: 0xDB4284)
self.tutorialButtonWidth.constant = 60
self.view.layoutIfNeeded()
})
UIView.addKeyframe(withRelativeStartTime: 0.1, relativeDuration: 0.1, animations: {
self.tutorialButton.tintColor = UIColor(rgb: 0x554E6E)
self.tutorialButtonWidth.constant = 30
self.view.layoutIfNeeded()
})
UIView.addKeyframe(withRelativeStartTime: 0.3, relativeDuration: 0.1, animations: {
self.tutorialButton.tintColor = UIColor(rgb: 0xDB4284)
self.tutorialButtonWidth.constant = 60
self.view.layoutIfNeeded()
})
UIView.addKeyframe(withRelativeStartTime: 0.4, relativeDuration: 0.1, animations: {
self.tutorialButton.tintColor = UIColor(rgb: 0x554E6E)
self.tutorialButtonWidth.constant = 30
self.view.layoutIfNeeded()
})
}) { (finishFlag) in
}
}
but when I run it , I've get an exception and like folowing:
Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[CAKeyframeAnimation setFromValue:]: unrecognized selector sent to instance 0x2820e06e0'

Answer 1

I realized how to solve this error. self.view.layoutIfNeeded() should be out of blocks so I did it and fix the error, So here the correct code :
func InitialAnimationToTutorialButton() {
UIView.animateKeyframes(withDuration: 1.5, delay: 0, options: [.repeat], animations: {
UIView.addKeyframe(withRelativeStartTime: 0, relativeDuration: 0.1, animations: {
self.tutorialButton.tintColor = UIColor(rgb: 0xDB4284)
self.tutorialButtonWidth.constant = 60
})
UIView.addKeyframe(withRelativeStartTime: 0.1, relativeDuration: 0.1, animations: {
self.tutorialButton.tintColor = UIColor(rgb: 0x554E6E)
self.tutorialButtonWidth.constant = 30
})
UIView.addKeyframe(withRelativeStartTime: 0.3, relativeDuration: 0.1, animations: {
self.tutorialButton.tintColor = UIColor(rgb: 0xDB4284)
self.tutorialButtonWidth.constant = 60
})
UIView.addKeyframe(withRelativeStartTime: 0.4, relativeDuration: 0.1, animations: {
self.tutorialButton.tintColor = UIColor(rgb: 0x554E6E)
self.tutorialButtonWidth.constant = 30
})
self.view.layoutIfNeeded()
}) { (finishFlag) in
}
}

Answer 2

A bug report has been filed on Open Radar for this issue https://openradar.appspot.com/32939029.
The reporter offers a few workarounds:
Not using a spring for the timing parameters
Putting the layoutIfNeeded call in the keyframe animation as well
Add an extension on CAKeyframeAnimation where you define a fromValue and ignore it being set
The 3rd solution is unlikely to affect your animation. You can add the CAKeyframeAnimation extension in Swift...
extension CAKeyframeAnimation {
#objc func setFromValue(_ value: Any?) {
}
}