Fastest way (performance wise) to darken UIView or CALayer

Question

I have a UIView / CALayer which I would like to darken. How can I as fast as possible darken it? Is there any way to avoid blending?

Following alternatives is known to me

• create a non-opaque CALayer and set background color and opacity and add it as a sublayer above main layer
• same as above using UIView (can be a tad slower...?)
• render view/layer to UIImage and doing drawing with CoreGraphics (is way too slow and content is dynamic/changing)

Answer 1

Create a non-opaque CALayer and set background color and opacity and add it as a sublayer above main layer