nicklockwood/FXBlurView — pull request #57 by CaseyB (2014-04-09 18:18:34+00:00)
Title: Using UIColor alpha and changing blend modes

I needed to have a blur view that darkened the view below it. I found that using kCGBlendModeNormal improved results across a range of colors and allowing the user to set the transparency in InterfaceBuilder helped get the effect we needed.