Drawing shadow with Quartz is slow on iPhone & iPad. Another way?

Question

I was pretty excited when I found out just how easy it is to add shadows to my UIViews on the iPhone/iPad.

Just add the framework in Xcode, add the import to the top

Answer 1

You should set the shadowPath property. It is how CoreGraphics is able to optimize shadows.

For example, if your view is an opaque rectangle:

self.contentView.layer.shadowPath = [UIBezierPath bezierPathWithRect:self.contentView.bounds].CGPath;

Answer 2

Thought I should make an answer because I didn't want this gem to get buried in the comments.

In addition to cobbal's answer above, which helped a lot, occulus also mentioned the following optimization for non-rectangular shadows, such as text shadows.

self.contentView.layer.shouldRasterize = YES;
// Fix visual degradation when rasterizing on high-density screens:
self.contentView.layer.rasterizationScale = [[UIScreen mainScreen] scale];