我希望通过从预定的字符串数组(如(红色、绿色、粉红色)中调用随机颜色来选择更改我的 swift 应用程序的背景颜色。
所以我有那个数组,我希望背景颜色被随机选择为这些颜色之一。
使用 self.bg.background color 导致 xcode 说字符串无法转换为 uicolor
下面是执行此操作的一种方法示例:
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()
您不能直接将任何字符串(如"Green"Pink")转换为UIColor对象。如果只想使用此功能,则必须创建将这些字符串与等效的 UIColor 对象匹配的自定义枚举。
意思是,虽然您可以在我编写的UIColor扩展支持的以下表单中使用字符串颜色。
- RGBA 字符串(字符串必须用空格"
0.5 0.6 0.7 1.0
"分隔 红色的 50% 的绿色的 70% 的蓝色 Alpha 的 100
%) - 十六进制字符串,例如
#ffffff
(相当于白色)等于 UIColor.white
要将这两种颜色字符串转换为 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)
)
}
}
要获取数组中存在的任何随机值,您可以在数组上创建一个扩展,如下所示。
extension Array {
func randomElement() -> Element {
return self[Int(arc4random_uniform(UInt32(self.count)))]
}
}
对于您的情况,您可以创建UIColor数组,如下所示
//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