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)
}
}
}
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])
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]
}
}
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)
}
}
Swift 3 -只使用纹理和SKSpriteNode，不需要UIView
import Foundation
import SpriteKit
class GradientSpriteNode : SKSpriteNode
{
convenience init(size: CGSize, colors: [UIColor], locations: [CGFloat])
{
let texture = GradientSpriteNode.texture(size: size, colors: colors, locations: locations)
self.init(texture: texture, color:SKColor.clear, size: texture.size())
}
private override init(texture: SKTexture!, color: SKColor, size: CGSize) {
super.init(texture: texture, color: color, size: size)
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
private static func texture(size: CGSize, colors: [UIColor], locations: [CGFloat]) -> SKTexture
{
UIGraphicsBeginImageContext(size)
let context = UIGraphicsGetCurrentContext()!
let gradient = CGGradient(colorsSpace: CGColorSpaceCreateDeviceRGB(), colors: colors.map{$0.cgColor} as CFArray, locations: locations)!
context.drawLinearGradient(gradient, start: CGPoint(x: size.width / 2, y: 0), end: CGPoint(x: size.width / 2, y: size.height), options: CGGradientDrawingOptions())
let image = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return SKTexture(image: image!)
}
}
用法:
let gradient = GradientSpriteNode(
size: CGSize(width: 100, height: 100),
colors: [UIColor.red, UIColor.blue],
locations: [0.0, 1.0])
addChild(gradient)
