将用户输入限制为Swift中的有效十进制数 [英] Limiting user input to a valid decimal number in Swift

问题描述

我已经找到了很多关于如何在objective-c中执行此操作的指南，但我希望看到更多以Swift为导向的方法。

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.

我有一个用户输入货币价格的UITextField。文本字段调用十进制键盘。但是，在iPad上，出现的键盘有一系列非小数符号。

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，我都想做到不能将非数字或超过一个小数的任何内容输入到字段中。如果输入小数，我想不可能输入第二个小数。如果删除小数，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.

关于如何在swift中正确执行此操作的任何想法？

Any ideas on how to properly do this in swift?

我也看到像这里发布的解决方案：
将UITextField限制为一个小数点Swift
但是我不知道在哪里放置函数或者我应该如何调用它们。每当我尝试在参数中输入NSRange时，我都会收到一条错误，表示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

这里是一个简单的例子：

Here is a simple example:

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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