setNeedsLayout and setNeedsDisplay

Question

What is the real difference between UIView methods setNeedsLayout and setNeedsDisplay?

As usual documentation is foggy about this.

Answer 1

Actually the documentation is pretty clear about this:

• setNeedsLayout will layout subviews

  Call this method on your application’s main thread when you want to adjust the layout of a view’s subviews.

• setNeedsDisplay will call for a redraw of your view (drawRect:, etc).

  You can use this method or the setNeedsDisplayInRect: to notify the system that your view’s contents need to be redrawn.