Question

I remember that when I was reading the Apple documentation, it would mention that when you call a function such as addSubview, you are adding a “layer of paint,” so to speak, and every time it is called, another layer is overlaid.

This should be an easy question to answer, but I had a hard time thinking of keywords to google for, so please excuse the asking of such a simple question.

How do I clear the “layers” of a custom UIView?

My situation, as it may be relevant: I have these “user cards” that are displayed on the screen. They are initialized with some user images. The cards stay the same, but I call a method in my custom UIView (the card UIView) to redraw the images when I want to display a different user. The problem is that some elements of this custom UIView are transparent, and redrawing these images each time builds on that transparency (an obvious problem).

Answer 1

In Core Graphics, what you draw is what gets shown. The painter’s analogy only refers to a single frame. So if you’re using drawRect, you just don’t cache the previous drawing.

But I suspect you’re talking about some UIKit stuff where you’ve added subviews or sublayers. This will remove those leftover views if you just want to clear everything:

for (UIView *view in customView) {
    [view removeFromSuperview];
}

for (CALayer *layer in customView.layer) {
    [layer removeFromSuperlayer];
}