Animate UIButton from current state - ios

Question

I want to create button which has "elastic" press down animation.
Animation description:
On press:
scale it on 80% in 0.1s
scale it on 90% in 0.1s // when pressed it should stay at 90% scale
On release:
scale it on 110% in 0.1s
scale it on 100% in 0.1s // when released - scale should finish at 100%
I tried to implement this with code:
-(void) pressedAnimation {
[UIView animateWithDuration:kAnimationTime
delay:0.0
options: UIViewAnimationOptionBeginFromCurrentState
animations:^{
self.transform = CGAffineTransformMakeScale(.8f, .8f);
}completion:^(BOOL finished){
if (finished) {
[UIView animateWithDuration:kAnimationTime
delay:0.0
options: UIViewAnimationOptionBeginFromCurrentState
animations:^{
self.transform = CGAffineTransformMakeScale(.9f, .9f);
}completion:^(BOOL finished){
}];
}
}];
}
-(void) releasedAnimation {
[UIView animateWithDuration:kAnimationTime
delay:0.0
options: UIViewAnimationOptionBeginFromCurrentState
animations:^{
self.transform = CGAffineTransformMakeScale(1.1f, 1.1f);
}completion:^(BOOL finished){
if (finished) {
[self.layer removeAllAnimations];
[UIView animateWithDuration:kAnimationTime
delay:0.0
options:UIViewAnimationOptionBeginFromCurrentState
animations:^{
self.transform = CGAffineTransformMakeScale(1.0f, 1.0f);
}completion:^(BOOL finished){
}];
}
}];
}
Animation works as expected only if "releasedAnimation" is called when "pressedAnimation" is already completed. Else I got very strange effects.
I tried to use [self.layer removeAllAnimations] in both methods but it doesn't work as expected. It seems like UIViewAnimationOptionBeginFromCurrentState doesn't work. What am I doing wrong? Is there a better way to create such an animation?

Answer 1

You could abstract this behavior out to a utility class. Try something like this:
For the .h:
+(void)buttonBobble:(UIButton *)button actionWhenDone:(void(^)(BOOL))action;
For .m:
+(void)buttonBobble:(UIButton *)button actionWhenDone:(void (^)(BOOL))action
{
button.transform = CGAffineTransformMakeScale(0.8f, 0.8f);
[UIView animateWithDuration:0.5f animations:^{
button.transform = CGAffineTransformMakeScale(1.0f, 1.0f);
}completion:action];
}
Of course, you may have to tweak this for the right look you want. You'll also want to add the UIViewAnimationOptionBeginFromCurrentState if you want it to pick up right where the button is at.