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

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)

}

SwiftUI:你可以使用线性梯度结构作为ZStack的第一个元素。作为ZStack的“底部”，它将作为背景色。AngularGradient和RadialGradient也可用。

import SwiftUI

struct ContentView: View {
    var body: some View {
        ZStack {
            LinearGradient(gradient: Gradient(colors: [.red, .blue]), startPoint: .top, endPoint: .bottom)
                .edgesIgnoringSafeArea(.all)
            // Put other content here; it will appear on top of the background gradient
        }
    }
}

如果你想使用HEX而不是RGBA，只需拖动一个新的空的.swift并添加下面提到的代码:

     import UIKit

    extension UIColor {
        convenience init(rgba: String) {
            var red:   CGFloat = 0.0
            var green: CGFloat = 0.0
            var blue:  CGFloat = 0.0
            var alpha: CGFloat = 1.0

            if rgba.hasPrefix("#") {
                let index   = advance(rgba.startIndex, 1)
                let hex     = rgba.substringFromIndex(index)
                let scanner = NSScanner(string: hex)
                var hexValue: CUnsignedLongLong = 0
                if scanner.scanHexLongLong(&hexValue) {
                    switch (count(hex)) {
                    case 3:
                        red   = CGFloat((hexValue & 0xF00) >> 8)       / 15.0
                        green = CGFloat((hexValue & 0x0F0) >> 4)       / 15.0
                        blue  = CGFloat(hexValue & 0x00F)              / 15.0
                    case 4:
                        red   = CGFloat((hexValue & 0xF000) >> 12)     / 15.0
                        green = CGFloat((hexValue & 0x0F00) >> 8)      / 15.0
                        blue  = CGFloat((hexValue & 0x00F0) >> 4)      / 15.0
                        alpha = CGFloat(hexValue & 0x000F)             / 15.0
                    case 6:
                        red   = CGFloat((hexValue & 0xFF0000) >> 16)   / 255.0
                        green = CGFloat((hexValue & 0x00FF00) >> 8)    / 255.0
                        blue  = CGFloat(hexValue & 0x0000FF)           / 255.0
                    case 8:
                        red   = CGFloat((hexValue & 0xFF000000) >> 24) / 255.0
                        green = CGFloat((hexValue & 0x00FF0000) >> 16) / 255.0
                        blue  = CGFloat((hexValue & 0x0000FF00) >> 8)  / 255.0
                        alpha = CGFloat(hexValue & 0x000000FF)         / 255.0
                    default:
                        print("Invalid RGB string, number of characters after '#' should be either 3, 4, 6 or 8")
                    }
                } else {
                    println("Scan hex error")
                }
            } else {
                print("Invalid RGB string, missing '#' as prefix")
            }
            self.init(red:red, green:green, blue:blue, alpha:alpha)
        }
}

类似地，拖动另一个空的.swift文件并添加下面提到的代码:

    class Colors {
    let colorTop = UIColor(rgba: "##8968CD").CGColor
    let colorBottom = UIColor(rgba: "#5D478B").CGColor

    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，在类下面实例化你的Color类，像这样:

let colors = Colors()

添加一个新函数:

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

在viewDidLoad中声明函数:

refresh()

你完成了:)) 如果与RGBA相比，使用HEX太容易了。: D

我做了一个UIView扩展应用一个基本的渐变到任何视图

extension UIView {
    func layerGradient() {
        let layer : CAGradientLayer = CAGradientLayer()
        layer.frame.size = self.frame.size
        layer.frame.origin = CGPointMake(0.0,0.0)
        layer.cornerRadius = CGFloat(frame.width / 20)

        let color0 = UIColor(red:250.0/255, green:250.0/255, blue:250.0/255, alpha:0.5).CGColor
        let color1 = UIColor(red:200.0/255, green:200.0/255, blue: 200.0/255, alpha:0.1).CGColor
        let color2 = UIColor(red:150.0/255, green:150.0/255, blue: 150.0/255, alpha:0.1).CGColor
        let color3 = UIColor(red:100.0/255, green:100.0/255, blue: 100.0/255, alpha:0.1).CGColor
        let color4 = UIColor(red:50.0/255, green:50.0/255, blue:50.0/255, alpha:0.1).CGColor
        let color5 = UIColor(red:0.0/255, green:0.0/255, blue:0.0/255, alpha:0.1).CGColor
        let color6 = UIColor(red:150.0/255, green:150.0/255, blue:150.0/255, alpha:0.1).CGColor

        layer.colors = [color0,color1,color2,color3,color4,color5,color6]
        self.layer.insertSublayer(layer, atIndex: 0)
    }
}       

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)