将用户输入限制为Swift中小于99999.99的有效十进制数

Question

我正在尝试在textField中为数量添加一些验证。我正在尝试允许用户使用十进制键盘添加有效数字。 用户可以添加小于100000的数字（99999.99,9999,9,1） 用户无法添加[12 ..，12.0.2,12.345,100.23456

等数字

这是我尝试过的。 如果我尝试将最大长度添加到5.i无法添加99999.99。 如果我将最大长度添加到8.我可以添加超过99999的数字。 希望你明白我的问题。谢谢你提前

   func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {

    let maxLength = 5
    var newString : NSString = ""

    if(textField.tag == 3){
        let currentString: NSString = tvAmount.text! as NSString
        newString  =
            currentString.replacingCharacters(in: range, with: string) as NSString

        // max 2 fractional digits allowed
        let newText = (textField.text! as NSString).replacingCharacters(in: range, with: string)
        let regex = try! NSRegularExpression(pattern: "\\..{3,}", options: [])
        let matches = regex.matches(in: newText, options:[], range:NSMakeRange(0, newText.characters.count))
        guard matches.count == 0 else { return false }

        if(newString.length < 5){
            switch string {
            case "0","1","2","3","4","5","6","7","8","9":
                return true
            case ".":
                let array = textField.text?.characters.map { String($0) }
                var decimalCount = 0
                for character in array! {
                    if character == "." {
                        decimalCount = decimalCount + 1
                    }
                }

                if decimalCount == 1 {
                    return false
                } else {
                    return true
                }
            default:
                let array = string.characters.map { String($0) }
                if array.count == 0 {
                    return true
                }
                return false
            }
        }
        else{
        }
    }
    return newString.length <= maxLength
}