Subclassing UIScrollView for drawing w/o views

Question

I'm contemplating subclassing UIScrollView (the way UITextView does) to draw a fairly large amount of text (formatted in ways that NSTextView can't).

So far the view won't actually scroll. I'm setting contentSize, and when I drag, I see the scroll indicator. But nothing changes (and I don't get a drawRect: message).

An alternate approach is to use a child view, and I've done this. The view can be over 5000 pixels high, however, and I'm a bit concerned about performance on an actual device.

(The other approach, be like UITableView, would be a huge pain -- I'm "porting" Mac Cocoa code, and a collection of views would be a huge architecture change.)

I've done some searching, but haven't found anyone who is using UIScrollView to do the drawing. Has anyone done this and know of any pitfalls?

Answer 1

All that UIScrollView does when the user scrolls is update its bounds rectangle, which causes the scroll views subviews to move. You could try setting the scroll view's contentMode to UIViewContentModeRedraw. From the docs:

UIViewContentModeRedraw
Redisplays the view when the bounds change by invoking the setNeedsDisplay method.