UICollectionView show hide animation issue - ios

Question

I am getting animation issue while hiding the UICollectionView. Show animation works fine but when I do the hide animation, it immediately hides the collection view without animation. This is the code :
#objc func openMenu(sender: UIButton) {
if sender.tag == 1 {
self.buttonView.tag = 2
self.arrow.image = UIImage(named: "arrowUp.png")
UIView.animate(withDuration: 0.7, animations: {
self.moduleView.frame.size.height = UIScreen.main.bounds.size.height - self.frame.size.height
}, completion: { _ in
})
} else {
self.buttonView.tag = 1
self.arrow.image = UIImage(named: "arrowDown.png")
UIView.animate(withDuration: 0.7, animations: {
self.moduleView.frame.size.height = 0
}, completion: { _ in
})
}
}
Output :
The strange thing is, I replaced the collection view with a simple UIView and it works fine. Bottom to top animation works perfectly. Code :
#objc func openMenu(sender: UIButton) {
if sender.tag == 1 {
self.buttonView.tag = 2
self.arrow.image = UIImage(named: "arrowUp.png")
UIView.animate(withDuration: 0.7, animations: {
self.testView.frame.size.height = UIScreen.main.bounds.size.height - self.frame.size.height
}, completion: { _ in
})
} else {
self.buttonView.tag = 1
self.arrow.image = UIImage(named: "arrowDown.png")
UIView.animate(withDuration: 0.7, animations: {
self.testView.frame.size.height = 0
}, completion: { _ in
})
}
}
Output :
Question : Why doesn't that work for UICollectionView ?
Initialisation :
UICollectionView :
self.moduleView = ModulesCollectionView(frame: CGRect(x: 0, y: 0, width: UIScreen.main.bounds.size.width, height: 0), collectionViewLayout: UICollectionViewLayout())
self.parentView.addSubView(self.moduleView)
UIView :
self.testView = UIView(frame: CGRect(x: 0, y: 0, width: UIScreen.main.bounds.size.width, height: 0))
self.parentView.addSubView(self.testView)

Answer 1

You need to use layoutSubViews() method for proper animation. Please change your code as below :
#objc func openMenu(sender: UIButton) {
if sender.tag == 1 {
self.buttonView.tag = 2
self.arrow.image = UIImage(named: "arrowUp.png")
UIView.animate(withDuration: 0.7, animations: {
self.moduleView.frame.size.height = UIScreen.main.bounds.size.height - self.frame.size.height
// Add this line
self.moduleView.layoutSubviews()
}, completion: { _ in
})
} else {
self.buttonView.tag = 1
self.arrow.image = UIImage(named: "arrowDown.png")
UIView.animate(withDuration: 0.7, animations: {
self.moduleView.frame.size.height = 0
// Add this line
self.moduleView.layoutSubviews()
}, completion: { _ in
})
}
}