IOS实例initWithCGColor

Question

我放弃了，这花费了太长而且我在任何地方都找不到列出的答案。

在 框架引用 中，UIColor 有一个函数 initWithCGColor。你怎么用这个？有人可以帮忙举个例子吗？我希望将颜色初始化为特定值!

https://developer.apple.com/library/ios/documentation/UIKit/Reference/UIColor_Class/index.html#//apple_ref/occ/instm/UIColor/initWithCGColor:

Answer 1

CGColorRef 是一个用于使用 Core 图形进行绘图的类。如果要用特定的 RGB 值初始化 UIColor 对象，请使用
- initWithRed:green:blue:alpha:

swift

let color = UIColor(red: 59/255.0, green: 136/255.0, blue: 195/255.0, alpha: 1)

objective-C

 UIColor * color = [UIColor colorWithRed:59/255.0f green:136/255.0f blue:195/255.0f alpha:1];

---

出于帮助目的，我为 UIColor 添加了一些有用的扩展/宏，以便初始化对象而不必考虑除以 255。我不是此代码的创建者，而是一位想要分享一些省时代码的感激用户:

swift

public extension UIColor{

    class func initRGBA(r r:CGFloat, g:CGFloat, b:CGFloat, a:CGFloat) -> UIColor
    {
        return UIColor(red:r/255, green: g/255, blue: b/255, alpha: a)
    }

    class func initRGB(r r:CGFloat, g:CGFloat, b:CGFloat) -> UIColor
    {
        return UIColor.initRGBA(r:r, g:g, b:b, a:1)
    }

    class func initRGBGRAY(gray:CGFloat) -> UIColor
    {
        return UIColor.initRGBA(r:gray, g:gray, b:gray, a:1)
    }
    convenience init(rgb: UInt) {
        self.init(
            red: CGFloat((rgb & 0xFF0000) >> 16) / 255.0,
            green: CGFloat((rgb & 0x00FF00) >> 8) / 255.0,
            blue: CGFloat(rgb & 0x0000FF) / 255.0,
            alpha: CGFloat(1.0)
        )
    }  
}

/// Let's initialize a color
let color = UIColor.initRGB(r: 24, g: 80, b: 145)

objective-C

#define RGBCOLOR(r,g,b) [UIColor colorWithRed:(r)/255.0f green:(g)/255.0f blue:(b)/255.0f alpha:1]
#define RGBACOLOR(r,g,b,a) [UIColor colorWithRed:(r)/255.0f green:(g)/255.0f blue:(b)/255.0f alpha:(a)]
#define RGBGRAYCOLOR(g) [UIColor colorWithRed:(g)/255.0f green:(g)/255.0f blue:(g)/255.0f alpha:1]

/// Let's initialize a color
UIColor * color = RGBCOLOR(87, 99, 132);