从UIColor中提取RGB值

Question

我见过人们在objective-c中这样做,但是我很快就遇到了麻烦.我从图片中获得了一个像素的颜色,但现在我需要采用单独的红色,绿色和蓝色值.这是我所拥有的(h,w和rgb是整数,image.getPixelColor(CGPoint)返回一个UIColor):

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

如何将此UIColor更改为红色,绿色和蓝色值？谢谢!

Answer 1

您可以将UIColor转换为CIColor,然后从中提取颜色组件,如下所示:

更新: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)
    }
}

用法:

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

您还可以使用函数getRed()并创建扩展来提取组件,如下所示,但结果将是可选的:

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

用法

let myColor = UIColor(red: 0.5, green: 1, blue: 0.25, alpha: 0.5)
if let myColorComponents = myColor.components {
    print(myColorComponents.red)   // 0.5
    print(myColorComponents.green) // 1.0
    print(myColorComponents.blue)  // 0.25
    print(myColorComponents.alpha) // 0.5
}

Answer 2

对于UIColor,您可以使用getRed方法:

let yourColor = UIColor(red: 0/255, green: 184/255, blue: 48/255, alpha: 1.0)
var r: CGFloat = 0, g: CGFloat = 0, b: CGFloat = 0, a: CGFloat = 0
yourColor.getRed(&r, green: &g, blue: &b, alpha: &a)
print("red: \(r), green: \(g), blue: \(b)")