Question

我希望通过从预定的字符串数组（例如（红色，绿色，粉色））调用随机颜色来更改我的swift应用程序的背景颜色。

所以我有那个数组，我希望随机选择背景颜色作为其中一种颜色。

使用self.bg.background颜色导致xcode表示字符串无法转换为uicolor

Answer 1

以下是一种实现此目的的方法示例：

import UIKit

extension Array {
  func randomElement() -> Element {
    return self[Int(arc4random_uniform(UInt32(self.count)))]
  }
}

extension UIColor {
  enum ColorEnum: String {
    case red   // = "red"
    case green // = "green"
    case blue  // = "blue"
    case pink  // = "pink"

    func toColor() -> UIColor {
      switch self {
      case .red:
        return .redColor()
      case .green:
        return .greenColor()
      case .blue:
        return .blueColor()
      case .pink:
        return UIColor(hue: 1.0, saturation: 0.25, brightness: 1.0, alpha: 1.0)
      }
    }
  }

  static func fromString(name: String) -> UIColor? {
    return ColorEnum(rawValue: name)?.toColor()
  }
}

let colors = ["red", "green", "pink"] // stored as String
UIColor.fromString(colors.randomElement())

let enumColors: [UIColor.ColorEnum] = [.red, .green, .pink] // stored as enum
enumColors.randomElement().toColor()

Answer 2

您无法直接转换任何字符串，例如＆＃34; Green＆＃34; ＆＃34;粉红＆＃34;到UIColor对象。如果你只想使用这个，那么你必须创建与这些字符串匹配的自定义枚举到相应的UIColor对象。

意思是你可以使用我编写的UIColor扩展支持的下面表格中的字符串颜色。

RGBA String（字符串必须用空格分隔＆＃34; 0.5 0.6 0.7 1.0＆＃34; 50％的红色60％的绿色70％的蓝色Alpha 100％）
例如十六进制字符串#ffffff（相当于白色）等于UIColor.white

要将这两个颜色字符串转换为UIColor，您可以使用以下UIColor扩展名

extension UIColor {


//Convert RGBA String to UIColor object
//"rgbaString" must be separated by space "0.5 0.6 0.7 1.0" 50% of Red 60% of Green 70% of Blue Alpha 100%
public convenience init?(rgbaString : String){
    self.init(ciColor: CIColor(string: rgbaString))
}

//Convert UIColor to RGBA String
func toRGBAString()-> String {

    var r: CGFloat = 0
    var g: CGFloat = 0
    var b: CGFloat = 0
    var a: CGFloat = 0
    self.getRed(&r, green: &g, blue: &b, alpha: &a)
    return "\(r) \(g) \(b) \(a)"

}
//return UIColor from Hexadecimal Color string
public convenience init?(hexString: String) {

        let r, g, b, a: CGFloat

        if hexString.hasPrefix("#") {
            let start = hexString.index(hexString.startIndex, offsetBy: 1)
            let hexColor = hexString.substring(from: start)

            if hexColor.characters.count == 8 {
                let scanner = Scanner(string: hexColor)
                var hexNumber: UInt64 = 0

                if scanner.scanHexInt64(&hexNumber) {
                    r = CGFloat((hexNumber & 0xff000000) >> 24) / 255
                    g = CGFloat((hexNumber & 0x00ff0000) >> 16) / 255
                    b = CGFloat((hexNumber & 0x0000ff00) >> 8) / 255
                    a = CGFloat(hexNumber & 0x000000ff) / 255
                    self.init(red: r, green: g, blue: b, alpha: a)
                    return
                }
            }
        }

        return nil
    }
// Convert UIColor to Hexadecimal String
func toHexString() -> String {
    var r: CGFloat = 0
    var g: CGFloat = 0
    var b: CGFloat = 0
    var a: CGFloat = 0
    self.getRed(&r, green: &g, blue: &b, alpha: &a)
    return String(
        format: "%02X%02X%02X",
        Int(r * 0xff),
        Int(g * 0xff),
        Int(b * 0xff)
    )
}

}

要获取Array中存在的任何随机值，您可以在Array上创建扩展，如下所示。

extension Array {
   func randomElement() -> Element {
        return self[Int(arc4random_uniform(UInt32(self.count)))]
   }
}

对于您的情况，您可以按如下方式创建UIColor数组

   //Define array to hold UIColor which will hold your Views background color  
    var arrOfColors = [UIColor]()

   //Create array of   RGBA String color like
    let arrRGBAStringColor = ["0.5 0.6 0.7 1.0","0.53 0.46 0.27 1.0","0.3 0.16 0.17 1.0"]

   //Create array of   Hexadecimal String color like
    let arrHexStringColor = ["#cccc41","#8e8e8e","#003300"]


    for stringColor in arrRGBAStringColor {

        //Use UIColor extension to convert RGBA string to UIColor
        if let color = UIColor(rgbaString : stringColor){
            arrOfColors.append(color)
        }
    }
    for stringColor in arrHexStringColor {
        //Use UIColor extension to convert Hexadecimal string to UIColor
        if let color = UIColor(hexString : stringColor){
            arrOfColors.append(color)
        }
    }

    //Now fetch any random color from your color array
    let randomColor = arrOfColors.randomElement()

    self.backgroundColor = randomColor

来自字符串数组的随机uicolor

2 个答案: