如何使用雨燕随机颜色

小开

You're going to need a function to produce random CGFloats in the range 0 to 1:

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

Then you can use this to create a random colour:

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

If you wanted a random alpha, just create another random number for that too.

You can now assign your view's background colour like so:

self.view.backgroundColor = .random()

小开

Make a function to generate random color:

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)
}

Now, you can call this function whenever you need random color.

self.view.backgroundColor = getRandomColor()

小开

For 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
)
}
}

For Swift 3 and above:

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)
}
}

Usage:

let myColor: UIColor = .random

小开

With Swift 4.2, you can simplify this by using the new random functions which have been added:

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)
}
}

There are more details here.

小开

func anotherGetRandomColor()->UIColor{


let newRed   = Double(arc4random_uniform(256))/255.0
let newGreen = Double(arc4random_uniform(256))/255.0
let newBlue  = Double(arc4random_uniform(256))/255.0


return UIColor(red: CGFloat(newRed), green: CGFloat(newGreen), blue: CGFloat(newBlue), alpha: 1.0)
}

小开

Swift 4.2 🔸

I'm adding this answer because it uses a different approach, and because many of the previous answers requires additional syntactic sugar, which in my opinion shouldn't be preferred. Vanilla Swift for the win.

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)
}
}

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Swift 4.2 Extension

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))
}


}

Usage:

let color = UIColor.random()

小开

Using an extension with an inline function to generate randoms

extension UIColor {
static func random() -> UIColor {


func random() -> CGFloat { return .random(in:0...1) }


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

小开

For random solid colors you can use UIColor HSB initializer and randomize only the hue:

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

小开

Swift 5.1

Make This function and generate Random color.

e.g. 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)
}

小开

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))
}
}

Usage:

let randomColor: Color = .random