如何应用梯度的背景视图的iOS Swift应用程序

我试图应用渐变作为一个视图(故事板的主视图)的背景色。代码运行，但没有任何变化。我使用xCode Beta 2和Swift。

代码如下:

class Colors {
  let colorTop = UIColor(red: 192.0/255.0, green: 38.0/255.0, blue: 42.0/255.0, alpha: 1.0)
  let colorBottom = UIColor(red: 35.0/255.0, green: 2.0/255.0, blue: 2.0/255.0, alpha: 1.0)

  let gl: CAGradientLayer

  init() {
    gl = CAGradientLayer()
    gl.colors = [ colorTop, colorBottom]
    gl.locations = [ 0.0, 1.0]
  }
}

然后在视图控制器中:

  let colors = Colors()

  func refresh() {
        view.backgroundColor = UIColor.clearColor()
        var backgroundLayer = colors.gl
        backgroundLayer.frame = view.frame
        view.layer.insertSublayer(backgroundLayer, atIndex: 0)
      }
    }
  }

当前回答

在Swift3试试这个:

 func addGradient(){

    let gradient:CAGradientLayer = CAGradientLayer()
    gradient.frame.size = self.viewThatHoldsGradient.frame.size
    gradient.colors = [UIColor.white.cgColor,UIColor.white.withAlphaComponent(0).cgColor] //Or any colors
    self.viewThatHoldsGradient.layer.addSublayer(gradient)

}

2015-11-29 10:27:18

其他回答

在Swift3试试这个:

 func addGradient(){

    let gradient:CAGradientLayer = CAGradientLayer()
    gradient.frame.size = self.viewThatHoldsGradient.frame.size
    gradient.colors = [UIColor.white.cgColor,UIColor.white.withAlphaComponent(0).cgColor] //Or any colors
    self.viewThatHoldsGradient.layer.addSublayer(gradient)

}

2015-11-29 10:27:18

使用以下代码:

extension UIView {
func applyGradient(colours: [UIColor]) -> Void {
 let gradient: CAGradientLayer = CAGradientLayer()
 gradient.frame = self.bounds
 gradient.colors = colours.map { $0.cgColor }
 gradient.startPoint = CGPoint(x : 0.0, y : 0.5)
 gradient.endPoint = CGPoint(x :1.0, y: 0.5)
 self.layer.insertSublayer(gradient, at: 0)
 }
}

像这样调用这个函数:

  self.mainView.applyGradient(colours: [.green, .blue])

2019-02-18 13:10:24

斯威夫特4

添加一个视图出口

@IBOutlet弱变量梯度视图：UIView！

为视图添加渐变

func setGradient() {
    let gradient: CAGradientLayer = CAGradientLayer()
    gradient.colors = [UIColor.red.cgColor, UIColor.blue.cgColor]
    gradient.locations = [0.0 , 1.0]
    gradient.startPoint = CGPoint(x: 0.0, y: 1.0)
    gradient.endPoint = CGPoint(x: 1.0, y: 1.0)
    gradient.frame = gradientView.layer.frame
    gradientView.layer.insertSublayer(gradient, at: 0)
}

2018-10-02 02:59:32

只是修改上面提到的答案。

func setGradientBackground() {
    let colorTop =  UIColor(red: 255.0/255.0, green: 149.0/255.0, blue: 0.0/255.0, alpha: 1.0).cgColor
    let colorBottom = UIColor(red: 255.0/255.0, green: 94.0/255.0, blue: 58.0/255.0, alpha: 1.0).cgColor
                
    let gradientLayer = CAGradientLayer()
    gradientLayer.colors = [colorTop, colorBottom]
    gradientLayer.locations = [0.0, 1.0]
    gradientLayer.frame = self.view.bounds
            
    self.view.layer.insertSublayer(gradientLayer, at:0)
}

然后在viewWillAppear中调用这个方法

override func viewWillAppear(_ animated: Bool) {
    setGradientBackground()
    super.viewWillAppear(animated)
}

2016-08-04 17:17:19

如果你需要改变渐变的方向你必须使用startPoint和endPoint。

let gradient: CAGradientLayer = CAGradientLayer()

gradient.colors = [UIColor.blue.cgColor, UIColor.red.cgColor]
gradient.locations = [0.0 , 1.0]
gradient.startPoint = CGPoint(x: 0.0, y: 1.0)
gradient.endPoint = CGPoint(x: 1.0, y: 1.0)
gradient.frame = CGRect(x: 0.0, y: 0.0, width: self.view.frame.size.width, height: self.view.frame.size.height)

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

2015-01-17 21:39:00

如何应用梯度的背景视图的iOS Swift应用程序

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