extension UIImage{    /**    获取图片中的像素颜色值    - parameter pos: 图片中的位置    - returns: 颜色值    */    func getPixelColor(pos:CGPoint)->(alpha: CGFloat, red: CGFloat, green: CGFloat,blue:CGFloat){ let pixelData=CGDataProviderCopyData(CGImageGetDataProvider(self.CGImage)) let data:UnsafePointer
    
      = CFDataGetBytePtr(pixelData) let pixelInfo: Int = ((Int(self.size.width) * Int(pos.y)) + Int(pos.x)) * 4 let r = CGFloat(data[pixelInfo]) / CGFloat(255.0) let g = CGFloat(data[pixelInfo+1]) / CGFloat(255.0) let b = CGFloat(data[pixelInfo+2]) / CGFloat(255.0) let a = CGFloat(data[pixelInfo+3]) / CGFloat(255.0) return (a,r,g,b) } }