给UIView渐变颜色(swift 4.2)

func makeGradientLayer(`for` object : UIView, startPoint : CGPoint, endPoint : CGPoint, gradientColors : [Any]) -> CAGradientLayer {
        let gradient: CAGradientLayer = CAGradientLayer()
        gradient.colors = gradientColors
        gradient.locations = [0.0 , 1.0]
        gradient.startPoint = startPoint
        gradient.endPoint = endPoint
        gradient.frame = CGRect(x: 0, y: 0, w: object.frame.size.width, h: object.frame.size.height)
        return gradient
    }

如何使用

let start : CGPoint = CGPoint(x: 0.0, y: 1.0)
let end : CGPoint = CGPoint(x: 1.0, y: 1.0)

let gradient: CAGradientLayer = makeGradientLayer(for: cell, startPoint: start, endPoint: end, gradientColors: [
                    UIColor(red:0.92, green:0.07, blue:0.4, alpha:1).cgColor,
                    UIColor(red:0.93, green:0.11, blue:0.14, alpha:1).cgColor
                    ])

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

斯威夫特3

在视图上添加一个渐变层

Bind your view outlet @IBOutlet var YOURVIEW : UIView! Define the CAGradientLayer() var gradient = CAGradientLayer() Here is the code you have to write in your viewDidLoad YOURVIEW.layoutIfNeeded() gradient.startPoint = CGPoint(x: CGFloat(0), y: CGFloat(1)) gradient.endPoint = CGPoint(x: CGFloat(1), y: CGFloat(0)) gradient.frame = YOURVIEW.bounds gradient.colors = [UIColor.red.cgColor, UIColor.green.cgColor] gradient.colors = [ UIColor(red: 255.0/255.0, green: 56.0/255.0, blue: 224.0/255.0, alpha: 1.0).cgColor,UIColor(red: 86.0/255.0, green: 13.0/255.0, blue: 232.0/255.0, alpha: 1.0).cgColor,UIColor(red: 16.0/255.0, green: 173.0/255.0, blue: 245.0/255.0, alpha: 1.0).cgColor] gradient.locations = [0.0 ,0.6 ,1.0] YOURVIEW.layer.insertSublayer(gradient, at: 0)

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。

快速的方法

This answer builds on the answers above and provides implementation for dealing with the problem of the gradient not being properly applied during rotation. It satisfies this problem by changing the gradient layer to a square so that rotation in all directions results in a correct gradient. The function signature includes a Swift variadic argument that allows one to pass in as many CGColorRef's (CGColor) as needed (see sample usage). Also provided is an example as a Swift extension so that one can apply a gradient to any UIView.

   func configureGradientBackground(colors:CGColorRef...){

        let gradient: CAGradientLayer = CAGradientLayer()
        let maxWidth = max(self.view.bounds.size.height,self.view.bounds.size.width)
        let squareFrame = CGRect(origin: self.view.bounds.origin, size: CGSizeMake(maxWidth, maxWidth))
        gradient.frame = squareFrame

        gradient.colors = colors
        view.layer.insertSublayer(gradient, atIndex: 0)
    }

使用方法:

在viewDidLoad ...

  override func viewDidLoad() {
        super.viewDidLoad()
        configureGradientBackground(UIColor.redColor().CGColor, UIColor.whiteColor().CGColor)
  }

扩展的实现

extension CALayer {


    func configureGradientBackground(colors:CGColorRef...){

        let gradient = CAGradientLayer()

        let maxWidth = max(self.bounds.size.height,self.bounds.size.width)
        let squareFrame = CGRect(origin: self.bounds.origin, size: CGSizeMake(maxWidth, maxWidth))
        gradient.frame = squareFrame

        gradient.colors = colors

        self.insertSublayer(gradient, atIndex: 0)
    }

}

扩展用例示例:

 override func viewDidLoad() {
        super.viewDidLoad()

        self.view.layer.configureGradientBackground(UIColor.purpleColor().CGColor, UIColor.blueColor().CGColor, UIColor.whiteColor().CGColor)
 }

这意味着渐变背景现在可以应用到任何UIControl，因为所有的控件都是UIViews(或子类)，所有的UIViews都有calayer。

斯威夫特4

扩展的实现

extension CALayer {
    public func configureGradientBackground(_ colors:CGColor...){

        let gradient = CAGradientLayer()

        let maxWidth = max(self.bounds.size.height,self.bounds.size.width)
        let squareFrame = CGRect(origin: self.bounds.origin, size: CGSize(width: maxWidth, height: maxWidth))
        gradient.frame = squareFrame

        gradient.colors = colors

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

扩展用例示例:

override func viewDidLoad() {
    super.viewDidLoad()

    self.view.layer.configureGradientBackground(UIColor.purple.cgColor, UIColor.blue.cgColor, UIColor.white.cgColor)
}

斯威夫特4:

正确显示IB中的梯度:

@IBDesignable public class GradientView: UIView {

    override open class var layerClass: AnyClass {
        return CAGradientLayer.classForCoder()
    }

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

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

    func configureGradientLayer() {
        let gradientLayer = layer as! CAGradientLayer
        gradientLayer.colors = [UIColor(hex: 0x003399).cgColor, UIColor(hex: 0x00297b).cgColor]
    }
}

试试这个对我来说很有魔力，

Objective - C

我已经设置了RGB渐变背景颜色为UIview

   UIView *view = [[UIView alloc] initWithFrame:CGRectMake(0,0,320,35)];
   CAGradientLayer *gradient = [CAGradientLayer layer];
   gradient.frame = view.bounds;
   gradient.startPoint = CGPointZero;
   gradient.endPoint = CGPointMake(1, 1);
   gradient.colors = [NSArray arrayWithObjects:(id)[[UIColor colorWithRed:34.0/255.0 green:211/255.0 blue:198/255.0 alpha:1.0] CGColor],(id)[[UIColor colorWithRed:145/255.0 green:72.0/255.0 blue:203/255.0 alpha:1.0] CGColor], nil];
   [view.layer addSublayer:gradient];

更新: Swift3 +

代码:

 var gradientView = UIView(frame: CGRect(x: 0, y: 0, width: 320, height: 35))
 let gradientLayer:CAGradientLayer = CAGradientLayer()
 gradientLayer.frame.size = self.gradientView.frame.size
 gradientLayer.colors = 
 [UIColor.white.cgColor,UIColor.red.withAlphaComponent(1).cgColor] 
//Use diffrent colors
 gradientView.layer.addSublayer(gradientLayer)

你可以添加渐变颜色的起点和终点。

  gradientLayer.startPoint = CGPoint(x: 0.0, y: 1.0)
  gradientLayer.endPoint = CGPoint(x: 1.0, y: 1.0)

更多细节请参考CAGradientLayer文档

希望这对一些人有所帮助。