Extract RGB Values From UIColor

Question

I have seen people do this in objective-c, but I am having trouble with this in swift. I have gotten the color of a pixel from a picture, but now I need to take the individual red, green, and blue values. Here is what I have (h, w, and rgb are integers and image.getPixelColor(CGPoint) returns a UIColor):

 xArry[h][w][rgb] = image.getPixelColor(CGPoint(x: w, y: h)) 

How do I change this UIColor into the red, green, and blue values? Thanks!

Answer 1

You can convert UIColor to CIColor and then extract the color components from it as follow:

Update: Xcode 8.3.2 • Swift 3.1

extension UIColor {     var coreImageColor: CIColor {         return CIColor(color: self)     }     var components: (red: CGFloat, green: CGFloat, blue: CGFloat, alpha: CGFloat) {         let coreImageColor = self.coreImageColor         return (coreImageColor.red, coreImageColor.green, coreImageColor.blue, coreImageColor.alpha)     } } 

usage:

let myColor = UIColor(red: 0.5, green: 1, blue: 0.25, alpha: 0.5) let myCIColor = myColor.coreImageColor let greencomponent = myColor.components.green let myColorComponents = myColor.components print(myColorComponents.red)   // 0.5 print(myColorComponents.green) // 1.0 print(myColorComponents.blue)  // 0.25 print(myColorComponents.alpha) // 0.5 

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You can also use the function getRed() and create an extension to extract the components as follow but the result would be optional:

extension UIColor {     typealias RGBA = (red: CGFloat, green: CGFloat, blue: CGFloat, alpha: CGFloat)     var rgba: RGBA? {         var (r, g, b, a): RGBA = (0, 0, 0, 0)         return getRed(&r, green: &g, blue: &b, alpha: &a) ? (r,g,b,a) : nil     }     var r: CGFloat? {         var red: CGFloat = .zero         return getRed(&red, green: nil, blue: nil, alpha: nil) ? red : nil     }     var g: CGFloat? {         var green: CGFloat = .zero         return getRed(nil, green: &green, blue: nil, alpha: nil) ? green : nil     }     var b: CGFloat? {         var blue: CGFloat = .zero         return getRed(nil, green: nil, blue: &blue, alpha: nil) ? blue : nil     }     var a: CGFloat? {         var alpha: CGFloat = .zero         return getRed(nil, green: nil, blue: nil, alpha: &alpha) ? alpha : nil     } } 

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Usage

let color = UIColor(red: 0.5, green: 1, blue: 0.25, alpha: 0.5) if let components = color.rgba {     print(components.red)   // 0.5     print(components.green) // 1.0     print(components.blue)  // 0.25     print(components.alpha) // 0.5 }  print(color.r ?? "nil")   // 0.5 print(color.g ?? "nil") // 1.0 print(color.b ?? "nil")  // 0.25 print(color.a ?? "nil") // 0.5