ios - 将文本字段输入限制为设定长度的数字输入

Question

我试图限制 3 个不同的文本字段，以便您只能在其中输入数字，并且您可以输入的位数也受到限制。

这是我的代码:

import Foundation
import UIKit
import Darwin

class View3on3 : UIViewController, UITextFieldDelegate {


@IBOutlet weak var APTeams: UITextField!
@IBOutlet weak var APRounds: UITextField!
@IBOutlet weak var APBreakers: UITextField!


override func viewDidLoad()
{
    super.viewDidLoad()
    initializeTextFields()
}


func initializeTextFields()
{
    APTeams.delegate = self
    APTeams.keyboardType = UIKeyboardType.NumberPad

    APRounds.delegate = self
    APRounds.keyboardType = UIKeyboardType.NumberPad

    APBreakers.delegate = self
    APBreakers.keyboardType = UIKeyboardType.NumberPad
}


override func didReceiveMemoryWarning()
{
    super.didReceiveMemoryWarning()
}


@IBAction func userTappedBackground(sender: AnyObject)
{
    view.endEditing(true)
}

func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool
{
    if string.characters.count == 0 {
        return true
    }

    let prospectiveText = (textField.text as NSString).stringByReplacingCharactersInRange(range, withString: String())

    switch textField {
    case APTeams:
        return prospectiveText.containsOnlyCharactersIn("0123456789") && count(prospectiveText) <= 3

    case APRounds:
        return prospectiveText.containsOnlyCharactersIn("0123456789") && count(prospectiveText) <= 1

    case APBreakers:
        return prospectiveText.containsOnlyCharactersIn("0123456789") && count(prospectiveText) <= 3

    default:
        return true
    }

}

}

它在这一行抛出错误:

let prospectiveText = (textField.text as NSString).stringByReplacingCharactersInRange(range, withString: String())

这么说 '字符串？'不可转换为 NSString

我按照这个网站上的教程进行操作: http://www.globalnerdy.com/2015/04/27/how-to-program-an-ios-text-field-that-takes-only-numeric-input-or-specific-characters-with-a-maximum-length/

我做错了什么？

PS。调用 NumberPad 的代码工作正常。当我删除限制位数的代码时，它工作正常。

Answer 1

或者您可以尝试一下，创建一个方法并在 View 加载时调用它:

func initializeTextFields({
digitsOnlyTextField.delegate = self
digitsOnlyTextField.keyboardType = UIKeyboardType.ASCIICapable

然后，您可以对文本字段进行硬编码，如下所示:

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

case digitsOnlyTextField:
return prospectiveText.containsOnlyCharactersIn("012346789")

尝试一下并向我提供一些反馈，祝你好运!