Swift 十六进制字符串转颜色

来源：互联网发布：郑州java培训机构靠谱编辑：程序博客网时间：2024/05/16 04:56

swift 3.0 语法有一定变化，相应字符串截取变化也不小，所以重写了一下取颜色的方法如下：

    func transferStringToColor(colorStr:String) -> UIColor {                var color = UIColor.red        var cStr : String = colorStr.trimmingCharacters(in: CharacterSet.whitespacesAndNewlines).uppercased()                if cStr.hasPrefix("#") {            let index = cStr.index(after: cStr.startIndex)            cStr = cStr.substring(from: index)        }        if cStr.characters.count != 6 {            return UIColor.black        }        //两种不同截取字符串的方法        let rRange = cStr.startIndex ..< cStr.index(cStr.startIndex, offsetBy: 2)        let rStr = cStr.substring(with: rRange)                let gRange = cStr.index(cStr.startIndex, offsetBy: 2) ..< cStr.index(cStr.startIndex, offsetBy: 4)        let gStr = cStr.substring(with: gRange)                let bIndex = cStr.index(cStr.endIndex, offsetBy: -2)        let bStr = cStr.substring(from: bIndex)                color = UIColor.init(colorLiteralRed: Float(changeToInt(numStr: rStr)) / 255, green: Float(changeToInt(numStr: gStr)) / 255, blue: Float(changeToInt(numStr: bStr)) / 255, alpha: 1)        return color    }}    func changeToInt(numStr:String) -> Int {        let str = numStr.uppercased()    var sum = 0    for i in str.utf8 {        //0-9 从48开始        sum = sum * 16 + Int(i) - 48        if i >= 65 {            //A~Z 从65开始，但初始值为10            sum -= 7        }    }    return sum}

当然，最好还是用Scanner来实现十六进制字符串转数字

 func transferStringToColor(_ colorStr:String) -> UIColor {                var color = UIColor.red        var cStr : String = colorStr.trimmingCharacters(in: CharacterSet.whitespacesAndNewlines).uppercased()                if cStr.hasPrefix("#") {            let index = cStr.index(after: cStr.startIndex)            cStr = cStr.substring(from: index)        }        if cStr.characters.count != 6 {            return UIColor.black        }                let rRange = cStr.startIndex ..< cStr.index(cStr.startIndex, offsetBy: 2)        let rStr = cStr.substring(with: rRange)                let gRange = cStr.index(cStr.startIndex, offsetBy: 2) ..< cStr.index(cStr.startIndex, offsetBy: 4)        let gStr = cStr.substring(with: gRange)                let bIndex = cStr.index(cStr.endIndex, offsetBy: -2)        let bStr = cStr.substring(from: bIndex)                var r:CUnsignedInt = 0, g:CUnsignedInt = 0, b:CUnsignedInt = 0;        Scanner(string: rStr).scanHexInt32(&r)        Scanner(string: gStr).scanHexInt32(&g)        Scanner(string: bStr).scanHexInt32(&b)                color = UIColor(red: CGFloat(r) / 255.0, green: CGFloat(g) / 255.0, blue: CGFloat(b) / 255.0, alpha: CGFloat(1))                return color    }

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