CGAffineTransform doesn't work with custom UIView - swift

Question

I'm trying to create a custom view class that is a popup with a UICollectionView on it. I've created functions to animate the view in and out, but only the animate out function is actually working.
I'm setting constraints as follows...
override init(frame: CGRect) {
super.init(frame: frame)
commonInit()
}
func commonInit(){
...
self.addSubview(collectionView)
collectionView.bottomAnchor.constraint(equalTo: self.safeAreaLayoutGuide.bottomAnchor).isActive = true
collectionView.leadingAnchor.constraint(equalTo: self.leadingAnchor).isActive = true
collectionView.trailingAnchor.constraint(equalTo: self.trailingAnchor).isActive = true
collectionView.heightAnchor.constraint(equalTo: self.heightAnchor, multiplier: 0.7).isActive = true
...
self.animateIn()
}
Then to handle the animation I'm using the following...
func animateIn(){
self.collectionView.transform = CGAffineTransform(translationX: 0, y: self.collectionView.frame.height)
self.blurredBackgroundView.alpha = 0
UIView.animate(withDuration: 0.5, animations: {
self.blurredBackgroundView.alpha = 1
self.collectionView.transform = .identity
})
}
And the animateOut function (which works) is...
func animateOut(){
UIView.animate(withDuration: 0.5, delay: 0, usingSpringWithDamping: 0.5, initialSpringVelocity: 1, options: .curveEaseIn, animations: {
self.collectionView.transform = CGAffineTransform(translationX: 0, y: self.collectionView.frame.height)
self.blurredBackgroundView.alpha = 0
}) { (complete) in
if complete {
self.removeFromSuperview()
}
}
}
But the initial CGAfineTransform isn't working so the view is appearing in its final position when it first appears. I'm confused as it's working perfectly for the animateOut function which is called when a button is pressed to close the popup.
Can anyone tell me what I'm doing wrong? I feel like there must be something basic I'm missing.
Thanks

Answer 1

You're trying to start your animation from an initializer, but by that time, the view isn't a part of view hierarchy. Since it's impossible to animate a view that isn't part of the view hierarchy, the transform is applied immediately. animateOut works fine, because when you call it the view is already displayed.
What you need to do is to call your animateIn function explicitly after the view has been added to view hierarchy
let yourView = YourView(frame: someFrame)
superview.addSubview(yourView)
yourView.animateIn()