Repeat while loop doesn't work - why? - ios

Question

I want an imageView in my viewController to "pulsate", that means become bigger and then tinier again and repeat that until the "start"-button was pressed. The problem is, that every time I call that function in the viewDidLoad() with a repeat-while-loop, it has got a breakpoint for whatever reason.
That's the part of my viewDidLoad():
repeat {
pulsate()
} while hasStarted == false
When I press the start button, hasStarted becomes true and it should stop pulsating. But it doesn't even start the function, it immediately calls an error. Where's the problem?
Here's my pulsate()-function
func pulsate()
{
frameOR = imageView.frame
frameNext = CGRect(x: imageView.frame.midX - 35, y: imageView.frame.midY - 35, width: 80, height: 80)
let frameVDL = CGRect(x: imageView.frame.midX - 150, y: imageView.frame.midY - 150, width: 300, height: 300)
if start == false
{
UIView.animate(withDuration: 2, animations: {
self.imageView.frame = frameVDL
}) { (finished) in
UIView.animate(withDuration: 2, animations: {
self.imageView.frame = self.frameOR
}, completion: nil)
}
}
}
Thank your for your help! Have a great day!

Answer 1

You can use UIView.animate's built-in options to really simplify what you're trying to do, and avoid locking up the thread.
Give this a try:
let frameOR = imageView.frame
let frameVDL = CGRect(x: imageView.frame.midX - 150, y: imageView.frame.midY - 150, width: 300, height: 300)
UIView.animate(withDuration: 2.0,
delay: 0.0,
options: [UIViewAnimationOptions.autoreverse, UIViewAnimationOptions.repeat],
animations: {
imageView.frame = frameVDL
},
completion: nil)
Your imageView should now be in a full "pulsing" loop, without needing any additional code. When you're ready to stop the animation, just call:
imageView.layer.removeAllAnimations()