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)
}
}
}
你提供给渐变的颜色必须是CGColor类型。设置CGColor数组为gl。colors。
正确的代码是:
class Colors {
var gl:CAGradientLayer!
init() {
let colorTop = UIColor(red: 192.0 / 255.0, green: 38.0 / 255.0, blue: 42.0 / 255.0, alpha: 1.0).cgColor
let colorBottom = UIColor(red: 35.0 / 255.0, green: 2.0 / 255.0, blue: 2.0 / 255.0, alpha: 1.0).cgColor
self.gl = CAGradientLayer()
self.gl.colors = [colorTop, colorBottom]
self.gl.locations = [0.0, 1.0]
}
}
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])
下面是在可重用的Util类文件中进行设置的变体
在你的Xcode项目中:
Create a new Swift class call it UI_Util.swift, and populate it as follows:
import Foundation
import UIKit
class UI_Util {
static func setGradientGreenBlue(uiView: UIView) {
let colorTop = UIColor(red: 15.0/255.0, green: 118.0/255.0, blue: 128.0/255.0, alpha: 1.0).cgColor
let colorBottom = UIColor(red: 84.0/255.0, green: 187.0/255.0, blue: 187.0/255.0, alpha: 1.0).cgColor
let gradientLayer = CAGradientLayer()
gradientLayer.colors = [ colorTop, colorBottom]
gradientLayer.locations = [ 0.0, 1.0]
gradientLayer.frame = uiView.bounds
uiView.layer.insertSublayer(gradientLayer, at: 0)
}
}
现在你可以像这样从任何ViewController调用这个函数:
类AbcViewController: UIViewController
override func viewDidLoad() {
super.viewDidLoad ()
UI_Util。setGradientGreen (uiView self。view):
｝
感谢katwal-Dipak对函数代码的回答
用这个自定义类扩展UIView。
GradientView.swift
import UIKit
class GradientView: UIView {
// Default Colors
var colors:[UIColor] = [UIColor.redColor(), UIColor.blueColor()]
override func drawRect(rect: CGRect) {
// Must be set when the rect is drawn
setGradient(colors[0], color2: colors[1])
}
func setGradient(color1: UIColor, color2: UIColor) {
let context = UIGraphicsGetCurrentContext()
let gradient = CGGradientCreateWithColors(CGColorSpaceCreateDeviceRGB(), [color1.CGColor, color2.CGColor], [0, 1])!
// Draw Path
let path = UIBezierPath(rect: CGRectMake(0, 0, frame.width, frame.height))
CGContextSaveGState(context)
path.addClip()
CGContextDrawLinearGradient(context, gradient, CGPointMake(frame.width / 2, 0), CGPointMake(frame.width / 2, frame.height), CGGradientDrawingOptions())
CGContextRestoreGState(context)
}
override func layoutSubviews() {
// Ensure view has a transparent background color (not required)
backgroundColor = UIColor.clearColor()
}
}
使用
gradientView。colors = [uiccolor . blackcolor ().colorWithAlphaComponent(0.8)， uiccolor . clearcolor ()]
结果
