Why are animated calls of UIView.isHidden = false compounded? - ios

Question

As you can see I'm having trouble formulating the question. Let me try to explain:
I'm using a search bar in my swift ios app. In order to get a desired animation effect I put it in a vertical stack view and then animate its isHidden property. This way search bar pushes down other children of the stack view as it animates in or pulls them up as it animates out. So far so good.
I've noticed a behavior that I think is strange. Could be a bug or could be me not understanding how things work. Basically if I call search bar hiding method x times in a row I need to call search bar showing method x times before it would show. I'd expect to have to make just one call to show search bar regardless of how many times I called hiding method. The issue doesn't exist other way around: if I call search bar showing code x times I only need to call hiding method once for it to go away. This doesn't happen if I set isHidden without animating it...
Here's a sample code and a video of the issue. I'd appreciate it if someone would help me understand this behavior.
class ViewController: UIViewController {
#IBOutlet weak var searchBar: UISearchBar! {
didSet {
searchBar.isHidden = true
}
}
#IBAction func showAction(_ sender: UIButton) {
expandSearch()
}
#IBAction func hideAction(_ sender: UIButton) {
collapseSearch()
}
private func expandSearch() {
UIView.animate(withDuration: 0.3){
self.searchBar.isHidden = false
}
}
private func collapseSearch() {
UIView.animate(withDuration: 0.3){
self.searchBar.isHidden = true
}
searchBar.resignFirstResponder()
}
}

Answer 1

You should not call an asynchronous animation of searchbar x times, instead of I suggest you to keep its state in variable, something like isSearchBarHidden,
and check it before show/hide search bar. You could use just one method with such signature showSearchBar(show: Bool) and setting this variable there.
#IBAction func showAction(_ sender: UIButton) {
showSearchBar(true)
}
#IBAction func hideAction(_ sender: UIButton) {
showSearchBar(false)
}
private
func showSearchBar(_ show: Bool) {
guard isSearchBarHidden != show else {
return
}
UIView.animate(withDuration: 0.3, animations: {
self.searchBar.isHidden = show
}) {
self.isSearchBarHidden = show
if !show && searchBar.isFerstResponder {
searchBar.resignFirstResponder
}
}
}
private
var isSearchBarHidden: Bool = true
Also it is a good practice to check if your textView/textField/searchBar isFirstResponder before call resignFirstResponder.
Hope it will help. Good luck!