问题
I'm trying to mask CALayer with a bitmap image. And I failed masking CALayer. My code is:
// 'PreloadViewController layerWithImageNamed' create a layer and set it's contents as specified UIImage.
CALayer* title = [PreloadViewController layerWithImageNamed:@"pinkhug_txt.png"];
[[[self view] layer] addSublayer:title];
CALayer* title_mask = [PreloadViewController layerWithImageNamed:@"hug_mask.png"];
[title setMask:title_mask];
The Apple reference says "CALayer in iPhone does not support mask property". But there is a postings about this on SO. Is it possible? Or what's wrong with my code?
回答1:
It was my fault and resolved now. I used an image without alpha channel. Unlike traditional masking techniques, CALayer uses mask image's alpha channel as mask data.
来源：https://stackoverflow.com/questions/2743169/is-it-possible-to-mask-calayer-in-iphone