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

        var futureStr = textField.text
        futureStr?.append(contentsOf: string)
        if futureStr == nil {
            futureStr = ""
        }
        var flag = -1
        var pointIndex = 0
        var isSeePoint = false
        for i in 0..<(futureStr!.characters.count) + 1 {
            let subStr1 = (futureStr! as NSString).substring(to: i)
            if subStr1.contains("."){
                if isSeePoint == false{
                    if i == 1 && string == "."{
                        return false
                    }
                    pointIndex = i
                    isSeePoint = true
//                    print("小数点的次序\(pointIndex)")
                }else{
                    if string == "."{
                        return false
                    }
                }
                flag += 1
                if flag > 2{
//                    print("插入的位置\(range.location)")
                    if range.location < pointIndex{
                        return true
                    }
                    return false
                }
            }
        }
        return true
    }