extension UIView {

    func applyGradient(isVertical: Bool, colorArray: [UIColor]) { 
        layer.sublayers?.filter({ $0 is CAGradientLayer }).forEach({ $0.removeFromSuperlayer() })
         
        let gradientLayer = CAGradientLayer()
        gradientLayer.colors = colorArray.map({ $0.cgColor })
        if isVertical {
            //top to bottom
            gradientLayer.locations = [0.0, 1.0]
        } else {
            //left to right
            gradientLayer.startPoint = CGPoint(x: 0.0, y: 0.5)
            gradientLayer.endPoint = CGPoint(x: 1.0, y: 0.5)
        }
        
        backgroundColor = .clear
        gradientLayer.frame = bounds
        layer.insertSublayer(gradientLayer, at: 0)
    }

}

使用

someView.applyGradient(isVertical: true, colorArray: [.green, .blue])

迅速实现:

var gradientLayerView: UIView = UIView(frame: CGRectMake(0, 0, view.bounds.width, 50))
var gradient: CAGradientLayer = CAGradientLayer()
gradient.frame = gradientLayerView.bounds
gradient.colors = [UIColor.grayColor().CGColor, UIColor.clearColor().CGColor]
gradientLayerView.layer.insertSublayer(gradient, atIndex: 0)
self.view.layer.insertSublayer(gradientLayerView.layer, atIndex: 0)

我已经在swift中实现了一个扩展:

斯威夫特3

extension UIView {
    func addGradientWithColor(color: UIColor) {
        let gradient = CAGradientLayer()
        gradient.frame = self.bounds
        gradient.colors = [UIColor.clear.cgColor, color.cgColor]

        self.layer.insertSublayer(gradient, at: 0)
    }
}

斯威夫特2.2

extension UIView {
    func addGradientWithColor(color: UIColor) {
        let gradient = CAGradientLayer()
        gradient.frame = self.bounds
        gradient.colors = [UIColor.clearColor().CGColor, color.CGColor]

        self.layer.insertSublayer(gradient, atIndex: 0)
    }
}

不，我可以像这样在每个视图上设置渐变:

myImageView.addGradientWithColor(UIColor.blue)

我已经在代码中实现了这一点。

UIView *view1 = [[UIView alloc] initWithFrame:CGRectMake(0.0f, 0.0f, self.view.frame.size.width, 31.0f)];
view1.backgroundColor = [UIColor clearColor];
CAGradientLayer *gradient = [CAGradientLayer layer];
gradient.frame = view1.bounds;
UIColor *topColor = [UIColor colorWithRed:132.0/255.0 green:222.0/255.0 blue:109.0/255.0 alpha:1.0];
UIColor *bottomColor = [UIColor colorWithRed:31.0/255.0 green:150.0/255.0 blue:99.0/255.0 alpha:1.0];
gradient.colors = [NSArray arrayWithObjects:(id)[topColor CGColor], (id)[bottomColor CGColor], nil];


[view1.layer insertSublayer:gradient atIndex:0];

现在我可以在视图中看到渐变。

基于Yuchen版本的简单swift视图

class GradientView: UIView {
    override class func layerClass() -> AnyClass { return CAGradientLayer.self }

    lazy var gradientLayer: CAGradientLayer = {
        return self.layer as! CAGradientLayer
    }()

    override init(frame: CGRect) {
        super.init(frame: frame)
    }

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
    }

}

然后你可以在初始化后使用gradientLayer，像这样…

someView.gradientLayer.colors = [UIColor.whiteColor().CGColor, UIColor.blackColor().CGColor]

你要找的是CAGradientLayer。每个UIView都有一个层-在这个层中你可以添加子层，就像你可以添加子视图一样。一个特定的类型是CAGradientLayer，在这里你给它一个颜色数组来渐变。

一个例子是这个简单的渐变视图包装器:

http://oleb.net/blog/2010/04/obgradientview-a-simple-uiview-wrapper-for-cagradientlayer/

注意，为了访问UIView的所有层部分，你需要包括QuartZCore框架。