CAGradientLayer

API:

@available(iOS 3.0, *)
open class CAGradientLayer : CALayer {

    /* The array of CGColorRef objects */

    open var colors: [Any]?


    /* a value in the range [0,1].*/

    open var locations: [NSNumber]?

    /* The start and end points of the gradient when drawn into the layer's
     * coordinate space. */

    open var startPoint: CGPoint
    open var endPoint: CGPoint


    /* 目前默认只支持 public let kCAGradientLayerAxial: String */
    open var type: String
}

CAGradientLayer 坐标系:

Practice:

func createUI1() {
    let gradientLayer = CAGradientLayer()
    gradientLayer.frame = self.gradientView.bounds
    self.gradientView.layer.addSublayer(gradientLayer)

    // 颜色分配
    gradientLayer.colors = [UIColor.blackColor().CGColor,UIColor.whiteColor().CGColor]

    // 颜色分割线位置( 默认 0，1 )
    gradientLayer.locations     = [0,1]

    // 起始点 坐标是 左上 （0，0）  右下 （1，1）
    gradientLayer.startPoint    = CGPointMake(0, 0)

    // 结束点
    gradientLayer.endPoint      = CGPointMake(1, 0)
}


func createUI2() {
    let gradientLayer = CAGradientLayer()
    gradientLayer.frame = self.gradientView2.bounds
    self.gradientView2.layer.addSublayer(gradientLayer)

    gradientLayer.colors = [UIColor.redColor().CGColor,UIColor.greenColor().CGColor,UIColor.blueColor().CGColor]

    gradientLayer.locations = [0.25,0.5,0.75]

    gradientLayer.startPoint = CGPointMake(0, 0.5)
    gradientLayer.endPoint = CGPointMake(1, 0.5)
}