Xcode 11•Swift 5.1

你可以像下面这样设计你自己的渐变视图:

@IBDesignable
public class Gradient: UIView {
    @IBInspectable var startColor:   UIColor = .black { didSet { updateColors() }}
    @IBInspectable var endColor:     UIColor = .white { didSet { updateColors() }}
    @IBInspectable var startLocation: Double =   0.05 { didSet { updateLocations() }}
    @IBInspectable var endLocation:   Double =   0.95 { didSet { updateLocations() }}
    @IBInspectable var horizontalMode:  Bool =  false { didSet { updatePoints() }}
    @IBInspectable var diagonalMode:    Bool =  false { didSet { updatePoints() }}

    override public class var layerClass: AnyClass { CAGradientLayer.self }

    var gradientLayer: CAGradientLayer { layer as! CAGradientLayer }

    func updatePoints() {
        if horizontalMode {
            gradientLayer.startPoint = diagonalMode ? .init(x: 1, y: 0) : .init(x: 0, y: 0.5)
            gradientLayer.endPoint   = diagonalMode ? .init(x: 0, y: 1) : .init(x: 1, y: 0.5)
        } else {
            gradientLayer.startPoint = diagonalMode ? .init(x: 0, y: 0) : .init(x: 0.5, y: 0)
            gradientLayer.endPoint   = diagonalMode ? .init(x: 1, y: 1) : .init(x: 0.5, y: 1)
        }
    }
    func updateLocations() {
        gradientLayer.locations = [startLocation as NSNumber, endLocation as NSNumber]
    }
    func updateColors() {
        gradientLayer.colors = [startColor.cgColor, endColor.cgColor]
    }
    override public func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {
        super.traitCollectionDidChange(previousTraitCollection)
        updatePoints()
        updateLocations()
        updateColors()
    }

}

Xcode 11 | Swift 5

如果有人正在寻找一个快速和简单的方法来添加一个渐变视图:

extension UIView {
    
    func addGradient(colors: [UIColor] = [.blue, .white], locations: [NSNumber] = [0, 2], startPoint: CGPoint = CGPoint(x: 0.0, y: 1.0), endPoint: CGPoint = CGPoint(x: 1.0, y: 1.0), type: CAGradientLayerType = .axial){
        
        let gradient = CAGradientLayer()
        
        gradient.frame.size = self.frame.size
        gradient.frame.origin = CGPoint(x: 0.0, y: 0.0)

        // Iterates through the colors array and casts the individual elements to cgColor
        // Alternatively, one could use a CGColor Array in the first place or do this cast in a for-loop
        gradient.colors = colors.map{ $0.cgColor }
        
        gradient.locations = locations
        gradient.startPoint = startPoint
        gradient.endPoint = endPoint
        
        // Insert the new layer at the bottom-most position
        // This way we won't cover any other elements
        self.layer.insertSublayer(gradient, at: 0)
    }
}

关于如何使用扩展的例子:

// Testing
view.addGradient()
        
// Two Colors
view.addGradient(colors: [.init(rgb: 0x75BBDB), .black], locations: [0, 3])
        
// Full Blown
view.addGradient(colors: [.init(rgb: 0x75BBDB), .black], locations: [0, 3], startPoint: CGPoint(x: 0.0, y: 1.5), endPoint: CGPoint(x: 1.0, y: 2.0), type: .axial)

可选地，使用以下命令输入十六进制数字。init(rgb: 0x75BBDB)

extension UIColor {
   convenience init(red: Int, green: Int, blue: Int) {
       self.init(red: CGFloat(red) / 255.0, green: CGFloat(green) / 255.0, blue: CGFloat(blue) / 255.0, alpha: 1.0)
   }

   convenience init(rgb: Int) {
       self.init(
           red: (rgb >> 16) & 0xFF,
           green: (rgb >> 8) & 0xFF,
           blue: rgb & 0xFF
       )
   }
}

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:

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)

对于swift应用CAGradientLayer到任何对象(水平和垂直)

func makeGradientColor(`for` object : AnyObject , startPoint : CGPoint , endPoint : CGPoint) -> CAGradientLayer {
    let gradient: CAGradientLayer = CAGradientLayer()

    gradient.colors = [(UIColor(red: 59.0/255.0, green: 187.0/255.0, blue: 182.0/255.0, alpha: 1.00).cgColor), (UIColor(red: 57.0/255.0, green: 174.0/255.0, blue: 236.0/255.0, alpha: 1.00).cgColor)]
    gradient.locations = [0.0 , 1.0]

    gradient.startPoint = startPoint
    gradient.endPoint = endPoint
    gradient.frame = CGRect(x: 0.0, y: 0.0, width: object.frame.size.width, height: 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 = self.makeGradientColor(for: vwTop, startPoint: start, endPoint: end)
vwTop.layer.insertSublayer(gradient, at: 0)

let start1 : CGPoint = CGPoint(x: 1.0, y: 1.0)
let end1 : CGPoint = CGPoint(x: 1.0, y: 0.0)
let gradient1: CAGradientLayer = self.makeGradientColor(for: vwTop, startPoint: start1, endPoint: end1)
vwBottom.layer.insertSublayer(gradient1, at: 0)

您可以在这里检查输出

我想添加一个渐变到一个视图，然后使用自动布局锚定它。

    class GradientView: UIView {

    private let gradient: CAGradientLayer = {
        let layer = CAGradientLayer()
        let topColor: UIColor = UIColor(red:0.98, green:0.96, blue:0.93, alpha:0.5)
        let bottomColor: UIColor = UIColor.white
        layer.colors = [topColor.cgColor, bottomColor.cgColor]
        layer.locations = [0,1]
        return layer
    }()

    init() {
        super.init(frame: .zero)
        gradient.frame = frame
        layer.insertSublayer(gradient, at: 0)
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    override func layoutSubviews() {
        super.layoutSubviews()
        gradient.frame = bounds

    }
}