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
}
}
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)
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()
}
}
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
}
}
