Question

This isn’t in reference to any particular code, but I’ve noticed that when I have a UIView that has a shadow added to it’s layer, the animation when rotating between interface orientations becomes much more laggy/choppy.

Has anyone noticed this issue or found a workaround?

Answer 1

There are things which are very expensive in terms of CPU time. Check it out in Instruments some time.

• shadows
• bezier paths
• bezier paths with dashes (really expensive)

Thats not a comprehensive list. I suspect gradients will be there too.

If you find these things are degrading your animation or redraw you will need to toggle them in the UIViewController methods.

-(void)willRotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation duration:(NSTimeInterval)duration
{
//disable shadows + expensive drawing
}

- (void)didRotateFromInterfaceOrientation:(UIInterfaceOrientation)fromInterfaceOrientation
{
//enable shadows + expensive drawing
}