如何使用 Swift 制作随机颜色函数?
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
}
}
您将需要一个函数来生成 0 到 1 范围内的随机
CGFloat
:
extension CGFloat {
static func random() -> CGFloat {
return CGFloat(arc4random()) / CGFloat(UInt32.max)
}
}
然后你可以用它来创建随机颜色:
extension UIColor {
static func random() -> UIColor {
return UIColor(
red: .random(),
green: .random(),
blue: .random(),
alpha: 1.0
)
}
}
如果您想要一个随机 alpha,只需为其创建另一个随机数即可。
您现在可以像这样指定视图的背景颜色:
self.view.backgroundColor = .random()
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
)
}
}
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)
}
}
let myColor: UIColor = .random
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()
对于随机纯色,您可以使用 UIColor HSB 初始化程序并仅随机化色调:
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
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))
}
}
let randomColor: Color = .random
使用 Swift 4.2,您可以通过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)
}
}
有更多详细信息这里。
斯威夫特 4.2 🔸
我添加这个答案是因为它使用了不同的方法,并且因为之前的许多答案需要额外的语法糖,在我看来,这不应该是首选。香草斯威夫特获胜。
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)
}
}
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))
}
}
用途:
let color = UIColor.random()
斯威夫特 5.1
制作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)
}
使用带有内联函数的扩展来生成随机数
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)
}
}
Swift 5.8.1 扩展
extension UIColor {
static var random: UIColor {
return .init(red: .random(in: 0...1), green: .random(in: 0...1), blue: .random(in: 0...1), alpha: 1)
}
}
用法
let randomColor = UIColor.random
print(randomColor)
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)
}
当您知道颜色是由数字组成时,很容易生成随机颜色。因此只需传入从
0.0
到 1.0
的随机值即可。但很多时候您实际上想保留随机颜色而不实际存储它。
以下是如何根据种子(例如
userID
)生成始终相同的随机颜色:
/// - Note: Make it `Color` for SwiftUI
extension UIColor {
static func random(seed: Int) -> Self {
var generator = RandomNumberGenerator(seed: seed)
return .init(
red: .random(in: (0...1), using: &generator),
green: .random(in: (0...1), using: &generator),
blue: .random(in: (0...1), using: &generator)
, alpha: 1 // Remove this line for the `SwiftUI.Color`
)
}
}
这是背后的随机数生成器:
struct RandomNumberGenerator: Swift.RandomNumberGenerator {
init(seed: Int) { srand48(seed) }
func next() -> UInt64 { UInt64(drand48() * Double(UInt64.max)) }
}
以下内容始终相同,并且每次运行(也不每次预览)都不会更改。
请注意,您可以按照您的需求来使用随机生成器