Question

I’m writing a program for iPhone that will first let the user take a photo, then will dynamically retrieve a colour of the place where the user taps on the image, and draw a rectangle of that colour. I have two relevant classes for this: AppViewController and AppView. The former contains all the UI elements and IBActions, the latter the position of last tap, the touches-handling methods and the drawRect (and a static method to get colour data at a given coords of an image).

What I wanted to do is to put the touch-handling (calling drawRect in touchesMoved/Ended) and the drawRect in the AppViewController. That doesn’t work, since that class doesn’t inherit from UIView, but from UIViewController. What’s the correct way to do that?

Another way to phrase that: How to constantly change something (well, constantly as long as the user is swiping across the screen) in a class that doesn’t support touch-detection methods?

(This probably doesn’t explain it well. Please ask clarifying questions).

Answer 1

I think the delegate pattern might be helpful to you in this situation. You could call your delegate’s shouldUpdateRectangle selector in touchesMoved/Ended.