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I have UIView subclass – actually a puzzle piece – with 2 different CGLayer initialized at initWithFrame.
In drawRect I have to blend this two layer, and the uppermost should have variable alpha depending on game-logic.
What is the best (most performance optimized) way to do this? Is there any CGLayer, or CGContext function that sets some alpha before drawing?
Set the
-opacityof the layer. Remember that the layer’s-opaquesetting must be NO. The default is NO, but it’s commonly set to YES for performance reasons.If you’re already doing
-drawInContext:, then you can experiment withCGContextSetAlpha(). Generally, though, you don’t use-drawRect:and layers at the same time. You usually let either the view or the layers do the drawing.