Swift UITextField 输入金额处理

限制输入最大金额 6 位
保留小数点后 2 位

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
        
        guard string == "." || string == "0" else {
            let newString = (textField.text! as NSString).replacingCharacters(in: range, with: string)
            
            let expression = "^[0-9]{0,6}?$*((\\.|,)[0-9]{0,2})?$"
            let regex = try! NSRegularExpression(pattern: expression, options: NSRegularExpression.Options.allowCommentsAndWhitespace)
            let numberOfMatches = regex.numberOfMatches(in: newString, options:.reportProgress, range: NSMakeRange(0, (newString as NSString).length))
            return numberOfMatches != 0
        }
        guard let text = textField.text else { return true }
        if text.range(of: ".") != nil && string == "." {
            return false
        }
        if text.range(of: ".") != nil{
            let list = textField.text!.components(separatedBy: ".")
            let last = list.last!
            return (last as NSString).length < 2
        }
        return true
    }

保留两位小数字符串处理

String.init(format:"%.2f", amountValue)

字符串转 CGFloat

func StringToFloat(str:String)->(CGFloat) {
        let string = str
        var cgFloat: CGFloat = 0
        if let doubleValue = Double(string) {
            cgFloat = CGFloat(doubleValue)
        }
        return cgFloat
}