添加颜色渐变的UIView

 1  //gradientLayer
 2     func addGradientViewLayer(){
 3         let contentView = UIView(frame: CGRectMake(100, 100, 100, 100))
 4         contentView.backgroundColor = UIColor.greenColor()
 5         self.view.addSubview(contentView)
 6         
 7         //create gradientLayer
 8         let gradientLayer : CAGradientLayer = CAGradientLayer()
 9         gradientLayer.frame = CGRectMake(0, 20, 100, 40);
10         //gradient colors
11         let colors = [UIColor.redColor().CGColor,UIColor.blackColor().CGColor]
12         
13         let locations = [0.0,1.0]
14         gradientLayer.colors = colors
15         gradientLayer.locations = locations
16         contentView.layer.insertSublayer(gradientLayer, atIndex: 0)
17         
18     }

 1 override func drawRect(rect: CGRect) {
 2         let colorSpace = CGColorSpaceCreateDeviceRGB()
 3         let context = UIGraphicsGetCurrentContext()
 4         let gradientStartColor = UIColor.greenColor()
 5         
 6         let gradientEndColor = UIColor.redColor()
 7         //colors
 8         let gradientColors : CFArray = [gradientStartColor.CGColor,gradientEndColor.CGColor]
 9         
10         //locations
11         let gradientLocations : [CGFloat] = [0.0,1.0]
12         let gradient = CGGradientCreateWithColors(colorSpace, gradientColors, gradientLocations)
13         
14         let pathRect = CGRectInset(self.bounds, 20, 20)
15         
16         let topPoint = CGPointMake(self.bounds.size.height/2, 20)
17         let bottomPoint = CGPointMake(self.bounds.size.width/2, self.bounds.size.height - 20)
18         
19         let roundedRectanglePath = UIBezierPath(roundedRect: pathRect, cornerRadius: 4)
20         CGContextSaveGState(context)
21         roundedRectanglePath.addClip()
22         CGContextDrawLinearGradient(context, gradient, bottomPoint, topPoint, 0)
23         CGContextRestoreGState(context)
24 
25     }