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)
}
}
}
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()
}
}
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)
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
}
}