Custom shape touchable area

Question

I have a shape like below and I want set it as background to my UIButton but touchable area is a rectangle, any suggestion to change touchable area to shape boarders?

Answer 1

Actually I found it on this like and working perfectly:

How to know that if the only visible area of a .png is touched in XCode (swift or objective C)

But must change code like below:

   func alphaFromPoint(point: CGPoint) -> CGFloat {
   var pixel: [UInt8] = [0, 0, 0, 0]
   let colorSpace = CGColorSpaceCreateDeviceRGB();
   let alphaInfo : CGBitmapInfo = CGBitmapInfo(rawValue: CGImageAlphaInfo.PremultipliedLast.rawValue)
   let context = CGBitmapContextCreate(&pixel, 1, 1, 8, 4, colorSpace, alphaInfo.rawValue) //need add .rawValue to alphaInfo

   CGContextTranslateCTM(context, -point.x, -point.y);

   self.layer.renderInContext(context!)

   let floatAlpha = CGFloat(pixel[3])
   return floatAlpha

}