I'm developing an app that allows for multitouch inputs, and am having trouble drawing using drawRect in my UIView. When more than one finger is on the screen, I need to draw a rect that encompasses all the UITouch inputs. Is there any best practice around this, or a way to draw multiple rects at the same time to avoid drawing a larger part of the screen again and again?
UIView has a method setNeedsDisplay(_:) that takes a rectangle to invalidate. You can call that repeatedly to force update of multiple small rectangular areas. The system will ask the view to re-draw those rectangles.