import UIKit
extension UIColor {
// 在extension中给系统的类扩充构造函数,只能扩充`便利构造函数`
convenience init(r : CGFloat, g : CGFloat, b : CGFloat, alpha : CGFloat = 1.0) {
self.init(red: r / 255.0, green: g / 255.0, blue: b / 255.0, alpha: alpha)
}
convenience init?(hex : String, alpha : CGFloat = 1.0) {
// 0xff0000
// 1.判断字符串的长度是否符合
guard hex.characters.count >= 6 else {
return nil
}
// 2.将字符串转成大写
var tempHex = hex.uppercased()
// 3.判断开头: 0x/#/##
if tempHex.hasPrefix("0x") || tempHex.hasPrefix("##") {
tempHex = (tempHex as NSString).substring(from: 2)
}
if tempHex.hasPrefix("#") {
tempHex = (tempHex as NSString).substring(from: 1)
}
// 4.分别取出RGB
// FF --> 255
var range = NSRange(location: 0, length: 2)
let rHex = (tempHex as NSString).substring(with: range)
range.location = 2
let gHex = (tempHex as NSString).substring(with: range)
range.location = 4
let bHex = (tempHex as NSString).substring(with: range)
// 5.将十六进制转成数字 emoji表情
var r : UInt32 = 0, g : UInt32 = 0, b : UInt32 = 0
Scanner(string: rHex).scanHexInt32(&r)
Scanner(string: gHex).scanHexInt32(&g)
Scanner(string: bHex).scanHexInt32(&b)
self.init(r : CGFloat(r), g : CGFloat(g), b : CGFloat(b))
}
class func randomColor() -> UIColor {
return UIColor(r: CGFloat(arc4random_uniform(256)), g: CGFloat(arc4random_uniform(256)), b: CGFloat(arc4random_uniform(256)))
}
}
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