从UIColor中提取RGB值 [英] Extract RGB Values From UIColor

问题描述

我见过人们在Objective-c中这样做，但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）：

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))

如何将此UIColor更改为红色，绿色和蓝色值？谢谢！

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

推荐答案

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

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

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

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你也可以使用函数getRed（）并创建一个扩展来提取组件，如下所示，但结果是可选的：

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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 {
    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
    }
}

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用法

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Usage

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
}

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