removeFromSuperview doesn't work with UIImageView - ios

Question

I add an image to my view by the following code if the count is zero and remove it otherwise:
var coverImageView = UIImageView()
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
if count == 0 {
let coverImage = UIImage(named: "AddFirstRecord")!
coverImageView = UIImageView(image: coverImage)
coverImageView.frame = CGRect(x: 20, y: 5, width: tableView.frame.width-20, height: 100)
view.addSubview(coverImageView)
} else {
DispatchQueue.main.async {
self.coverImageView.removeFromSuperview()
}
}
}
The problem is that it adds the image to the view, but removeFromSuperview does not work. (I made sure that it reaches to the else condition by debugging). I did the process in the main queue as well to be sure that the problem does not relate to threads. I wonder where is the origin of the issue?

Answer 1

In viewWillAppear the view still is not prepared completely to view. So removingFromSuperview does not have any effects. Instead, we should do the action inside viewDidLayoutSubviews:
override func viewDidLayoutSubviews() {
super.viewDidLayoutSubviews()
if fetchedResultsController.fetchedObjects?.count == 0 {
let coverImage = UIImage(named: "AddFirstRecord")!
coverImageView.image = coverImage
coverImageView.frame = CGRect(x: 20, y: 5, width: tableView.frame.width-20, height: 100)
view.addSubview(coverImageView)
} else {
coverImageView.removeFromSuperview()
}
}
From Apple Documentation :
viewDidLayoutSubviews()
Called to notify the view controller that its
view has just laid out its subviews.
Your view controller can override this method to make changes after
the view lays out its subviews. The default implementation of this
method does nothing.