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)
}
}
}
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)
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
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:
易于使用的扩展swift 3
extension CALayer {
func addGradienBorder(colors:[UIColor] = [UIColor.red,UIColor.blue], width:CGFloat = 1) {
let gradientLayer = CAGradientLayer()
gradientLayer.frame = CGRect(origin: .zero, size: self.bounds.size)
gradientLayer.startPoint = CGPoint(x:0.0, y:0.5)
gradientLayer.endPoint = CGPoint(x:1.0, y:0.5)
gradientLayer.colors = colors.map({$0.cgColor})
let shapeLayer = CAShapeLayer()
shapeLayer.lineWidth = width
shapeLayer.path = UIBezierPath(rect: self.bounds).cgPath
shapeLayer.fillColor = nil
shapeLayer.strokeColor = UIColor.black.cgColor
gradientLayer.mask = shapeLayer
self.addSublayer(gradientLayer)
}
}
用你的观点，例子
yourView.addGradienBorder(color: UIColor.black, opacity: 0.1, offset: CGSize(width:2 , height: 5), radius: 3, viewCornerRadius: 3.0)
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)
}
