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

有一个名为Chameleon (https://github.com/viccalexander/Chameleon)的库可以用于渐变颜色。它甚至有渐变的风格来实现。这就是如何在swift 4 podfile中添加它 “变色龙框架/Swift”,:git => 'https://github.com/ViccAlexander/Chameleon.git',:branch => 'wip/swift4'

import ChameleonFramework

let colors:[UIColor] = [
  UIColor.flatPurpleColorDark(), 
  UIColor.flatWhiteColor()
]
view.backgroundColor = GradientColor(.TopToBottom, frame: view.frame, colors: colors)

其他回答

我有这些扩展:

@IBDesignable class GradientView: UIView {
    @IBInspectable var firstColor: UIColor = UIColor.red
    @IBInspectable var secondColor: UIColor = UIColor.green

    @IBInspectable var vertical: Bool = true

    lazy var gradientLayer: CAGradientLayer = {
        let layer = CAGradientLayer()
        layer.colors = [firstColor.cgColor, secondColor.cgColor]
        layer.startPoint = CGPoint.zero
        return layer
    }()

    //MARK: -

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

        applyGradient()
    }

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

        applyGradient()
    }

    override func prepareForInterfaceBuilder() {
        super.prepareForInterfaceBuilder()
        applyGradient()
    }

    override func layoutSubviews() {
        super.layoutSubviews()
        updateGradientFrame()
    }

    //MARK: -

    func applyGradient() {
        updateGradientDirection()
        layer.sublayers = [gradientLayer]
    }

    func updateGradientFrame() {
        gradientLayer.frame = bounds
    }

    func updateGradientDirection() {
        gradientLayer.endPoint = vertical ? CGPoint(x: 0, y: 1) : CGPoint(x: 1, y: 0)
    }
}

@IBDesignable class ThreeColorsGradientView: UIView {
    @IBInspectable var firstColor: UIColor = UIColor.red
    @IBInspectable var secondColor: UIColor = UIColor.green
    @IBInspectable var thirdColor: UIColor = UIColor.blue

    @IBInspectable var vertical: Bool = true {
        didSet {
            updateGradientDirection()
        }
    }

    lazy var gradientLayer: CAGradientLayer = {
        let layer = CAGradientLayer()
        layer.colors = [firstColor.cgColor, secondColor.cgColor, thirdColor.cgColor]
        layer.startPoint = CGPoint.zero
        return layer
    }()

    //MARK: -

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

        applyGradient()
    }

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

        applyGradient()
    }

    override func prepareForInterfaceBuilder() {
        super.prepareForInterfaceBuilder()
        applyGradient()
    }

    override func layoutSubviews() {
        super.layoutSubviews()
        updateGradientFrame()
    }

    //MARK: -

    func applyGradient() {
        updateGradientDirection()
        layer.sublayers = [gradientLayer]
    }

    func updateGradientFrame() {
        gradientLayer.frame = bounds
    }

    func updateGradientDirection() {
        gradientLayer.endPoint = vertical ? CGPoint(x: 0, y: 1) : CGPoint(x: 1, y: 0)
    }
}

@IBDesignable class RadialGradientView: UIView {

    @IBInspectable var outsideColor: UIColor = UIColor.red
    @IBInspectable var insideColor: UIColor = UIColor.green

    override func awakeFromNib() {
        super.awakeFromNib()

        applyGradient()
    }

    func applyGradient() {
        let colors = [insideColor.cgColor, outsideColor.cgColor] as CFArray
        let endRadius = sqrt(pow(frame.width/2, 2) + pow(frame.height/2, 2))
        let center = CGPoint(x: bounds.size.width / 2, y: bounds.size.height / 2)
        let gradient = CGGradient(colorsSpace: nil, colors: colors, locations: nil)
        let context = UIGraphicsGetCurrentContext()

        context?.drawRadialGradient(gradient!, startCenter: center, startRadius: 0.0, endCenter: center, endRadius: endRadius, options: CGGradientDrawingOptions.drawsBeforeStartLocation)
    }

    override func draw(_ rect: CGRect) {
        super.draw(rect)

        #if TARGET_INTERFACE_BUILDER
            applyGradient()
        #endif
    }
}

用法:

清洁的代码,让你传递任何UIColor到GradientLayer类的实例:

class GradientLayer {

    let gradientLayer: CAGradientLayer
    let colorTop: CGColor
    let colorBottom: CGColor

    init(colorTop: UIColor, colorBottom: UIColor) {
        self.colorTop = colorTop.CGColor
        self.colorBottom = colorBottom.CGColor
        gradientLayer = CAGradientLayer()
        gradientLayer.colors = [colorTop, colorBottom]
        gradientLayer.locations = [0.0, 1.0]
    }
}

对于那些想要Objective C版本的答案的人。经过测试,在iOS13上运行

// Done here so that constraints have completed and the frame is correct.
- (void) viewDidLayoutSubviews { 
    [super viewDidLayoutSubviews];
    UIColor *colorTop = [UIColor colorWithRed:(CGFloat)192.0/255.0 green: 38.0/255.0 blue: 42.0/255.0 alpha:1.0];
    UIColor *colorBottom = [UIColor colorWithRed: 35.0/255.0 green: 2.0/255.0 blue: 2.0/255.0 alpha: 1.0];
    CAGradientLayer *gl = [CAGradientLayer new];
    [gl setColors:@[(id)[colorTop CGColor], (id)[colorBottom CGColor]]];
    [gl setLocations:@[@0.0f, @1.0f]];
    self.view.backgroundColor = [UIColor clearColor];
    CALayer *backgroundLayer = gl;
    backgroundLayer.frame = self.view.frame;
    [self.view.layer insertSublayer:backgroundLayer atIndex:0];
}

试试这个,对我很有效,

  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)

要了解更多详细描述,请参阅Best Answer或从Apple跟踪CAGradientLayer

希望这是对某人的帮助。

我把罗希特·西索迪亚和米高梅的答案混在了一起

// MARK: - Gradient

public enum CAGradientPoint {
    case topLeft
    case centerLeft
    case bottomLeft
    case topCenter
    case center
    case bottomCenter
    case topRight
    case centerRight
    case bottomRight
    var point: CGPoint {
        switch self {
        case .topLeft:
            return CGPoint(x: 0, y: 0)
        case .centerLeft:
            return CGPoint(x: 0, y: 0.5)
        case .bottomLeft:
            return CGPoint(x: 0, y: 1.0)
        case .topCenter:
            return CGPoint(x: 0.5, y: 0)
        case .center:
            return CGPoint(x: 0.5, y: 0.5)
        case .bottomCenter:
            return CGPoint(x: 0.5, y: 1.0)
        case .topRight:
            return CGPoint(x: 1.0, y: 0.0)
        case .centerRight:
            return CGPoint(x: 1.0, y: 0.5)
        case .bottomRight:
            return CGPoint(x: 1.0, y: 1.0)
        }
    }
}

extension CAGradientLayer {

    convenience init(start: CAGradientPoint, end: CAGradientPoint, colors: [CGColor], type: CAGradientLayerType) {
        self.init()
        self.frame.origin = CGPoint.zero
        self.startPoint = start.point
        self.endPoint = end.point
        self.colors = colors
        self.locations = (0..<colors.count).map(NSNumber.init)
        self.type = type
    }
}

extension UIView {

    func layerGradient(startPoint:CAGradientPoint, endPoint:CAGradientPoint ,colorArray:[CGColor], type:CAGradientLayerType ) {
        let gradient = CAGradientLayer(start: .topLeft, end: .topRight, colors: colorArray, type: type)
        gradient.frame.size = self.frame.size
        self.layer.insertSublayer(gradient, at: 0)
    }
}

To Use写:-

        btnUrdu.layer.cornerRadius = 25
        btnUrdu.layer.masksToBounds = true 
        btnUrdu.layerGradient(startPoint: .centerRight, endPoint: .centerLeft, colorArray: [UIColor.appBlue.cgColor, UIColor.appLightBlue.cgColor], type: .axial)

输出: