如何将渐变应用于 iOS Swift 应用程序的背景视图

问题描述

我正在尝试应用渐变作为视图(故事板的主视图)的背景颜色.代码运行，但没有任何变化.我使用的是 xCode Beta 2 和 Swift.

I'm trying to apply a gradient as the background color of a View (main view of a storyboard). The code runs, but nothing changes. I'm using xCode Beta 2 and 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)
      }
    }
  }

推荐答案

您提供给渐变的颜色必须是 CGColor 类型.所以将你的 CGColor 数组设置为 gl.colors.

The Colors you're providing to gradient must be of type CGColor. So set your array of CGColor to gl.colors.

正确的代码是:

class Colors {
    var gl:CAGradientLayer!

    init() {
        let colorTop = UIColor(red: 192.0 / 255.0, green: 38.0 / 255.0, blue: 42.0 / 255.0, alpha: 1.0).cgColor
        let colorBottom = UIColor(red: 35.0 / 255.0, green: 2.0 / 255.0, blue: 2.0 / 255.0, alpha: 1.0).cgColor

        self.gl = CAGradientLayer()
        self.gl.colors = [colorTop, colorBottom]
        self.gl.locations = [0.0, 1.0]
    }
}

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