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)
}
}
如果你想使用HEX而不是RGBA，只需拖动一个新的空的.swift并添加下面提到的代码:
import UIKit
extension UIColor {
convenience init(rgba: String) {
var red: CGFloat = 0.0
var green: CGFloat = 0.0
var blue: CGFloat = 0.0
var alpha: CGFloat = 1.0
if rgba.hasPrefix("#") {
let index = advance(rgba.startIndex, 1)
let hex = rgba.substringFromIndex(index)
let scanner = NSScanner(string: hex)
var hexValue: CUnsignedLongLong = 0
if scanner.scanHexLongLong(&hexValue) {
switch (count(hex)) {
case 3:
red = CGFloat((hexValue & 0xF00) >> 8) / 15.0
green = CGFloat((hexValue & 0x0F0) >> 4) / 15.0
blue = CGFloat(hexValue & 0x00F) / 15.0
case 4:
red = CGFloat((hexValue & 0xF000) >> 12) / 15.0
green = CGFloat((hexValue & 0x0F00) >> 8) / 15.0
blue = CGFloat((hexValue & 0x00F0) >> 4) / 15.0
alpha = CGFloat(hexValue & 0x000F) / 15.0
case 6:
red = CGFloat((hexValue & 0xFF0000) >> 16) / 255.0
green = CGFloat((hexValue & 0x00FF00) >> 8) / 255.0
blue = CGFloat(hexValue & 0x0000FF) / 255.0
case 8:
red = CGFloat((hexValue & 0xFF000000) >> 24) / 255.0
green = CGFloat((hexValue & 0x00FF0000) >> 16) / 255.0
blue = CGFloat((hexValue & 0x0000FF00) >> 8) / 255.0
alpha = CGFloat(hexValue & 0x000000FF) / 255.0
default:
print("Invalid RGB string, number of characters after '#' should be either 3, 4, 6 or 8")
}
} else {
println("Scan hex error")
}
} else {
print("Invalid RGB string, missing '#' as prefix")
}
self.init(red:red, green:green, blue:blue, alpha:alpha)
}
}
类似地，拖动另一个空的.swift文件并添加下面提到的代码:
class Colors {
let colorTop = UIColor(rgba: "##8968CD").CGColor
let colorBottom = UIColor(rgba: "#5D478B").CGColor
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，在类下面实例化你的Color类，像这样:
let colors = Colors()
添加一个新函数:
func refresh() {
view.backgroundColor = UIColor.clearColor()
var backgroundLayer = colors.gl
backgroundLayer.frame = view.frame
view.layer.insertSublayer(backgroundLayer, atIndex: 0)
}
在viewDidLoad中声明函数:
refresh()
你完成了:))
如果与RGBA相比，使用HEX太容易了。: D
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。
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)
