如何使用Swift制作随机颜色

Question

如何使用Swift制作随机颜色功能？

import UIKit

class ViewController: UIViewController {

    var randomNumber = arc4random_uniform(20)
    var randomColor = arc4random()

    //Color Background randomly
    func colorBackground() {

        // TODO: set a random color
        view.backgroundColor = UIColor.yellow

    }
}

Answer 1

您将需要一个函数来生成CGFloat0到1范围内的随机s:

extension CGFloat {
    static func random() -> CGFloat {
        return CGFloat(arc4random()) / CGFloat(UInt32.max)
    }
}

然后你可以用它来创建一个随机颜色:

extension UIColor {
    static func random() -> UIColor {
        return UIColor(red:   .random(),
                       green: .random(),
                       blue:  .random(),
                       alpha: 1.0)
    }
}

如果你想要一个随机的alpha,只需为它创建另一个随机数.

您现在可以像这样分配视图的背景颜色:

self.view.backgroundColor = .random()

Answer 2

对于Swift 4.2

extension UIColor {
    static var random: UIColor {
        return UIColor(red: .random(in: 0...1),
                       green: .random(in: 0...1),
                       blue: .random(in: 0...1),
                       alpha: 1.0)
    }
}

对于Swift 3及以上版本:

extension CGFloat {
    static var random: CGFloat {
        return CGFloat(arc4random()) / CGFloat(UInt32.max)
    }
}

extension UIColor {
    static var random: UIColor {
        return UIColor(red: .random, green: .random, blue: .random, alpha: 1.0)
    }
}

用法:

let myColor: UIColor = .random

Answer 3

创建一个生成随机颜色的函数:

func getRandomColor() -> UIColor {
     //Generate between 0 to 1
     let red:CGFloat = CGFloat(drand48())   
     let green:CGFloat = CGFloat(drand48()) 
     let blue:CGFloat = CGFloat(drand48())  

     return UIColor(red:red, green: green, blue: blue, alpha: 1.0)
}

现在,您可以在需要随机颜色时调用此函数.

self.view.backgroundColor = getRandomColor()

Answer 4

SwiftUI - Swift 5

import SwiftUI

extension Color {
    static var random: Color {
        return Color(red: .random(in: 0...1),
                     green: .random(in: 0...1),
                     blue: .random(in: 0...1))
    }
}

用法：

let randomColor: Color = .random

Answer 5

对于随机的纯色，可以使用UIColor HSB初始化程序，并且仅对色调进行随机化：

extension UIColor {
    static var random: UIColor {
        return .init(hue: .random(in: 0...1), saturation: 1, brightness: 1, alpha: 1)
    }
}

let color1: UIColor = .random
let color2: UIColor = .random
let color3: UIColor = .random
let color4: UIColor = .random
let color5: UIColor = .random

Answer 6

使用Swift 4.2,您可以使用已添加的新随机函数来简化此操作:

extension UIColor {
  static func random () -> UIColor {
    return UIColor(
      red: CGFloat.random(in: 0...1),
      green: CGFloat.random(in: 0...1),
      blue: CGFloat.random(in: 0...1),
      alpha: 1.0)
  }
}

还有更多的细节在这里.

Answer 7

斯威夫特4.2

我添加此答案是因为它使用了不同的方法，并且由于许多以前的答案都需要附加的语法糖，因此我认为不应将其作为首选。Vanilla Swift赢得了胜利。

extension UIColor {
    /**
     * Returns random color
     * ## Examples: 
     * self.backgroundColor = UIColor.random
     */
    static var random: UIColor {
        let r:CGFloat  = .random(in: 0...1)
        let g:CGFloat  = .random(in: 0...1)
        let b:CGFloat  = .random(in: 0...1)
        return UIColor(red: r, green: g, blue: b, alpha: 1)
    }
}

Answer 8

Swift 4.2扩展

extension UIColor {

    convenience init(red: Int, green: Int, blue: Int) {
        assert(red >= 0 && red <= 255, "Invalid red component")
        assert(green >= 0 && green <= 255, "Invalid green component")
        assert(blue >= 0 && blue <= 255, "Invalid blue component")

        self.init(red: CGFloat(red) / 255.0, green: CGFloat(green) / 255.0, blue: CGFloat(blue) / 255.0, alpha: 1.0)
    }

    convenience init(rgb: Int) {
        self.init(
            red: (rgb >> 16) & 0xFF,
            green: (rgb >> 8) & 0xFF,
            blue: rgb & 0xFF
        )
    }

    static func random() -> UIColor {
        return UIColor(rgb: Int(CGFloat(arc4random()) / CGFloat(UINT32_MAX) * 0xFFFFFF))
    }

}

用法：

let color = UIColor.random()

Answer 9

斯威夫特 5.1

使用此函数并生成随机颜色。

例如view.backgroundColor = random()

func random() -> UIColor {
        return UIColor(red: .random(in: 0...1),
                       green: .random(in: 0...1),
                       blue: .random(in: 0...1),
                       alpha: 1.0)
    }