UIView scaling during animation

Question

I\'ve got a custom UIView to show a tiled image.

    - (void)drawRect:(CGRect)rect
    {
        ...
        CGContextRef context = UIGraphicsGetCurrentConte         


        

Answer 1

If Core Animation had to call back to your code for every animation frame it would never be as fast as it is, and animation of custom properties has been a long requested feature and FAQ for CA on the Mac.

Using UIViewContentModeRedraw is on the right track, and is also the best you'll get from CA. The problem is from the UIKit point of view the frame only has two values: the value at the beginning of the transition and the value at the end of the transition, and that's what you're seeing. If you look at the Core Animation architecture documents you'll see how CA has a private representation of all layer properties and their values changing over time. That's where the frame interpolation is happening, and you can't be notified of changes to that as they happen.

So the only way is to use an NSTimer (or performSelector:withObject:afterDelay:) to change the view frame over time, the old fashioned way.