添加颜色渐变的UIView

UIView颜色渐变,可以直接使用CAGradientLayer或者重写drawRect:都可以实现渐变的效果,其中本质都是一样的.

比较简单的渐变只要设置过渡的颜色,和开始的位置,若不设置位置,会默认平均分.

1.使用 CAGradientLayer

 //gradientLayer

 //gradientLayer
    func addGradientViewLayer(){
        let contentView = UIView(frame: CGRectMake(100, 100, 100, 100))
        contentView.backgroundColor = UIColor.greenColor()
        self.view.addSubview(contentView)
        
        //create gradientLayer
        let gradientLayer : CAGradientLayer = CAGradientLayer()
        gradientLayer.frame = CGRectMake(0, 20, 100, 40);
        //gradient colors
        let colors = [UIColor.redColor().CGColor,UIColor.blackColor().CGColor]
        
        let locations = [0.0,1.0]
        gradientLayer.colors = colors
        gradientLayer.locations = locations
        contentView.layer.insertSublayer(gradientLayer, atIndex: 0)
        
    }

效果图,绿色背景View上的红黑渐变

2.drawRect:自定义

override func drawRect(rect: CGRect) {
        let colorSpace = CGColorSpaceCreateDeviceRGB()
        let context = UIGraphicsGetCurrentContext()
        let gradientStartColor = UIColor.greenColor()
        
        let gradientEndColor = UIColor.redColor()
        //colors
        let gradientColors : CFArray = [gradientStartColor.CGColor,gradientEndColor.CGColor]
        
        //locations
        let gradientLocations : [CGFloat] = [0.0,1.0]
        let gradient = CGGradientCreateWithColors(colorSpace, gradientColors, gradientLocations)
        
        let pathRect = CGRectInset(self.bounds, 20, 20)
        
        let topPoint = CGPointMake(self.bounds.size.height/2, 20)
        let bottomPoint = CGPointMake(self.bounds.size.width/2, self.bounds.size.height - 20)
        
        let roundedRectanglePath = UIBezierPath(roundedRect: pathRect, cornerRadius: 4)
        CGContextSaveGState(context)
        roundedRectanglePath.addClip()
        CGContextDrawLinearGradient(context, gradient, bottomPoint, topPoint, 0)
        CGContextRestoreGState(context)

    }

效果,红绿渐变