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)
}
}
}
试试这个，对我很有效，
var gradientView = UIView(frame: CGRect(x: 0, y: 0, width: 320, height: 35))
let gradientLayer:CAGradientLayer = CAGradientLayer()
gradientLayer.frame.size = self.gradientView.frame.size
gradientLayer.colors =
[UIColor.white.cgColor,UIColor.red.withAlphaComponent(1).cgColor]
//Use diffrent colors
gradientView.layer.addSublayer(gradientLayer)
你可以添加渐变颜色的起点和终点。
gradientLayer.startPoint = CGPoint(x: 0.0, y: 1.0)
gradientLayer.endPoint = CGPoint(x: 1.0, y: 1.0)
要了解更多详细描述，请参阅Best Answer或从Apple跟踪CAGradientLayer
希望这是对某人的帮助。
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()
}
}
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)
只是修改上面提到的答案。
func setGradientBackground() {
let colorTop = UIColor(red: 255.0/255.0, green: 149.0/255.0, blue: 0.0/255.0, alpha: 1.0).cgColor
let colorBottom = UIColor(red: 255.0/255.0, green: 94.0/255.0, blue: 58.0/255.0, alpha: 1.0).cgColor
let gradientLayer = CAGradientLayer()
gradientLayer.colors = [colorTop, colorBottom]
gradientLayer.locations = [0.0, 1.0]
gradientLayer.frame = self.view.bounds
self.view.layer.insertSublayer(gradientLayer, at:0)
}
然后在viewWillAppear中调用这个方法
override func viewWillAppear(_ animated: Bool) {
setGradientBackground()
super.viewWillAppear(animated)
}
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
我有这些扩展:
@IBDesignable class GradientView: UIView {
@IBInspectable var firstColor: UIColor = UIColor.red
@IBInspectable var secondColor: UIColor = UIColor.green
@IBInspectable var vertical: Bool = true
lazy var gradientLayer: CAGradientLayer = {
let layer = CAGradientLayer()
layer.colors = [firstColor.cgColor, secondColor.cgColor]
layer.startPoint = CGPoint.zero
return layer
}()
//MARK: -
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
applyGradient()
}
override init(frame: CGRect) {
super.init(frame: frame)
applyGradient()
}
override func prepareForInterfaceBuilder() {
super.prepareForInterfaceBuilder()
applyGradient()
}
override func layoutSubviews() {
super.layoutSubviews()
updateGradientFrame()
}
//MARK: -
func applyGradient() {
updateGradientDirection()
layer.sublayers = [gradientLayer]
}
func updateGradientFrame() {
gradientLayer.frame = bounds
}
func updateGradientDirection() {
gradientLayer.endPoint = vertical ? CGPoint(x: 0, y: 1) : CGPoint(x: 1, y: 0)
}
}
@IBDesignable class ThreeColorsGradientView: UIView {
@IBInspectable var firstColor: UIColor = UIColor.red
@IBInspectable var secondColor: UIColor = UIColor.green
@IBInspectable var thirdColor: UIColor = UIColor.blue
@IBInspectable var vertical: Bool = true {
didSet {
updateGradientDirection()
}
}
lazy var gradientLayer: CAGradientLayer = {
let layer = CAGradientLayer()
layer.colors = [firstColor.cgColor, secondColor.cgColor, thirdColor.cgColor]
layer.startPoint = CGPoint.zero
return layer
}()
//MARK: -
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
applyGradient()
}
override init(frame: CGRect) {
super.init(frame: frame)
applyGradient()
}
override func prepareForInterfaceBuilder() {
super.prepareForInterfaceBuilder()
applyGradient()
}
override func layoutSubviews() {
super.layoutSubviews()
updateGradientFrame()
}
//MARK: -
func applyGradient() {
updateGradientDirection()
layer.sublayers = [gradientLayer]
}
func updateGradientFrame() {
gradientLayer.frame = bounds
}
func updateGradientDirection() {
gradientLayer.endPoint = vertical ? CGPoint(x: 0, y: 1) : CGPoint(x: 1, y: 0)
}
}
@IBDesignable class RadialGradientView: UIView {
@IBInspectable var outsideColor: UIColor = UIColor.red
@IBInspectable var insideColor: UIColor = UIColor.green
override func awakeFromNib() {
super.awakeFromNib()
applyGradient()
}
func applyGradient() {
let colors = [insideColor.cgColor, outsideColor.cgColor] as CFArray
let endRadius = sqrt(pow(frame.width/2, 2) + pow(frame.height/2, 2))
let center = CGPoint(x: bounds.size.width / 2, y: bounds.size.height / 2)
let gradient = CGGradient(colorsSpace: nil, colors: colors, locations: nil)
let context = UIGraphicsGetCurrentContext()
context?.drawRadialGradient(gradient!, startCenter: center, startRadius: 0.0, endCenter: center, endRadius: endRadius, options: CGGradientDrawingOptions.drawsBeforeStartLocation)
}
override func draw(_ rect: CGRect) {
super.draw(rect)
#if TARGET_INTERFACE_BUILDER
applyGradient()
#endif
}
}
用法:
