iOS颜色渐变

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方法1：

//图片边缘模糊

let colorLayer =CAGradientLayer()

colorLayer.frame =circleImageIcon.frame

colorLayer.position =circleImageIcon.center

//设置渐变颜色及透明度

colorLayer.colors = [UIColor(red:250 /255.0, green:250 /255.0, blue:250 /255.0, alpha:0.1).CGColor,UIColor(red:250 /255.0, green:250 /255.0, blue:250 /255.0, alpha:0.5).CGColor,UIColor(red:250 /255.0, green:250 /255.0, blue:250 /255.0, alpha:1.0).CGColor]

//颜色分割线

colorLayer.locations = [0.5,0.75]

//颜色起止点

colorLayer.startPoint =CGPointMake(0.5,0)

colorLayer.endPoint =CGPointMake(1,0)

circleImageIcon.layer.insertSublayer(colorLayer, atIndex:0)

方法2

新建一个类继承于UIVIew，重写drawRect方法，

//获取上下文

let context =UIGraphicsGetCurrentContext()

// let gradient: CGGradientRef

let colorSpace =CGColorSpaceCreateDeviceRGB()

//颜色渐变组件,一组四个数字分别对应rgb透明度

let componets:[CGFloat] = [220.0,220.0, 220.0,0.1,220.0,220.0,220.0, 1]

//定义渐变位置

let locations:[CGFloat] = [0,1]

let gradient =CGGradientCreateWithColorComponents(colorSpace, componets, locations,2)!

//绘制线性渐变

CGContextDrawLinearGradient(context, gradient,CGPointMake(0, rect.size.height),CGPointMake(rect.size.width, rect.size.height),CGGradientDrawingOptions.DrawsAfterEndLocation)

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