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)
}
}
}
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
}
}
很容易
// MARK: - Gradient
extension CAGradientLayer {
enum Point {
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)
}
}
}
convenience init(start: Point, end: Point, colors: [CGColor], type: CAGradientLayerType) {
self.init()
self.startPoint = start.point
self.endPoint = end.point
self.colors = colors
self.locations = (0..<colors.count).map(NSNumber.init)
self.type = type
}
}
像这样使用:-
let fistColor = UIColor.white
let lastColor = UIColor.black
let gradient = CAGradientLayer(start: .topLeft, end: .topRight, colors: [fistColor.cgColor, lastColor.cgColor], type: .radial)
gradient.frame = yourView.bounds
yourView.layer.addSublayer(gradient)
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
}
}
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]
}
}
只需要指定视图的框架，你想在其中显示渐变颜色。
let firstColor = UIColor(red: 69/255, green: 90/255, blue: 195/255, alpha: 1.0).CGColor
let secondColor = UIColor(red: 230/255, green: 44/255, blue: 75/255, alpha: 1.0).CGColor
let gradientLayer = CAGradientLayer()
gradientLayer.colors = [ firstColor, secondColor]
gradientLayer.locations = [ 0.0, 1.0]
gradientLayer.frame = CGRectMake(0, 0, 375, 64)// You can mention frame here
self.view.layer.addSublayer(gradientLayer)
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
