在 Swift 中将用户输入限制为有效的十进制数 [英] Limiting user input to a valid decimal number in Swift

问题描述

我在 Objective-c 中找到了很多关于如何做到这一点的指南，但我希望看到一种更面向 Swift 的方式来做到这一点.

I have found a lot of guides on how to do this in objective-c, but I would like to see a more Swift-oriented way of doing this.

我有一个 UITextField，用户可以在其中输入货币价格.文本字段调用十进制键盘.然而，在 iPad 上，出现的键盘上有一整套非十进制符号.

I have a UITextField that a user enters a currency price into. The textfield calls a decimal pad keyboard. However, on the iPad, the keyboard that comes up has a whole range of non-decimal symbols.

基本上，对于每一次按键，我想让非数字或超出单个小数的任何内容都无法输入到该字段中.如果输入了小数，我想让输入第二个小数成为不可能.如果小数被删除，我想确保用户可以再次输入小数.

Basically, for every single key press, I would like to make it impossible for a non-number or anything beyond a single decimal to be typed into the field. If a decimal is typed, I would like to make it impossible to enter a second decimal. If the decimal is deleted, I'd like to make sure the user can enter a decimal again.

有关如何快速正确执行此操作的任何想法?

Any ideas on how to properly do this in swift?

我也看到了类似这里发布的解决方案:将 UITextField 限制为一位小数点 Swift但我不知道在哪里放置函数或如何调用它们.每当我尝试在参数中放入 NSRange 时，我都会收到一个错误，指出我没有正确创建范围.

I also see solutions like the ones posted here: Limit UITextField to one decimal point Swift But I have no idea where to place the functions or how I should call them. Whenever I try to put in NSRange in the parameters, I receive an error that I am not creating a range properly.

推荐答案

这是一个简单的例子:

import UIKit

class ViewController: UIViewController, UITextFieldDelegate {

    @IBOutlet weak var textField: UITextField!

    override func viewDidLoad() {
        super.viewDidLoad()

        self.textField.delegate = self

    }

    //Textfield delegates
    func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool { // return NO to not change text

        switch string {
        case "0","1","2","3","4","5","6","7","8","9":
            return true
        case ".":
            let array = Array(textField.text)
            var decimalCount = 0
            for character in array {
                if character == "." {
                    decimalCount++
                }
            }

            if decimalCount == 1 {
                return false
            } else {
                return true
            }
        default:
            let array = Array(string)
            if array.count == 0 {
                return true
            }
            return false
        }
    }
}

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