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)
}
}
}
用这个自定义类扩展UIView。
GradientView.swift
import UIKit
class GradientView: UIView {
// Default Colors
var colors:[UIColor] = [UIColor.redColor(), UIColor.blueColor()]
override func drawRect(rect: CGRect) {
// Must be set when the rect is drawn
setGradient(colors[0], color2: colors[1])
}
func setGradient(color1: UIColor, color2: UIColor) {
let context = UIGraphicsGetCurrentContext()
let gradient = CGGradientCreateWithColors(CGColorSpaceCreateDeviceRGB(), [color1.CGColor, color2.CGColor], [0, 1])!
// Draw Path
let path = UIBezierPath(rect: CGRectMake(0, 0, frame.width, frame.height))
CGContextSaveGState(context)
path.addClip()
CGContextDrawLinearGradient(context, gradient, CGPointMake(frame.width / 2, 0), CGPointMake(frame.width / 2, frame.height), CGGradientDrawingOptions())
CGContextRestoreGState(context)
}
override func layoutSubviews() {
// Ensure view has a transparent background color (not required)
backgroundColor = UIColor.clearColor()
}
}
使用
gradientView。colors = [uiccolor . blackcolor ().colorWithAlphaComponent(0.8)， uiccolor . clearcolor ()]
结果
