如何检查UITextField何时更改？

Question

我试图检查文本字段何时更改,相当于textView使用的函数 - textViewDidChange到目前为止我已经这样做了:

  func textFieldDidBeginEditing(textField: UITextField) {
        if self.status.text == "" && self.username.text == "" {
            self.topRightButton.enabled = false
        } else {   
            self.topRightButton.enabled = true
        }
    }

哪种工作,但topRightButton只要按下文本字段就启用,我希望只有在实际输入文本时才能启用它？

Answer 1

迅速

textfield.addTarget(self, action: #selector(ViewControllerr.textFieldDidChange(_:)), for: UIControl.Event.editingChanged)

然后你可以打电话给你的功能!

@objc func textFieldDidChange(_ textField: UITextField) {

}

SWIFT 2.2

textField.addTarget(self, action: #selector(textFieldDidChange(_:)), for: .editingChanged)

和

func textFieldDidChange(_ textField: UITextField) {

}

SWIFT 3&swift 4.1

textField.addTarget(self, action: #selector(YourViewController.textFieldDidChange(_:)), forControlEvents: UIControlEvents.EditingChanged)

和

func textFieldDidChange(textField: UITextField) {
    //your code
}

斯威夫特4

[textField addTarget:self action:@selector(textFieldDidChange:) forControlEvents:UIControlEventEditingChanged];

Objective-C的

-(void)textFieldDidChange :(UITextField *) textField{
    //your code
}

和textFieldDidChange方法是

textfield.addTarget(self, action: #selector(ViewControllerr.textFieldDidChange(_:)), for: UIControl.Event.editingChanged)

Answer 2

您可以在界面构建器中建立此连接.

1. 在故事板中,单击屏幕顶部的助理编辑器(中间的两个圆圈).

2. Ctrl +单击界面构建器中的文本字段.

3. 从EditingChanged拖动到助手视图中的视图控制器类内部.

4. 为您的函数命名(例如"textDidChange"),然后单击"连接".

Answer 3

Swift 3.0

textField.addTarget(self, action: #selector(textFieldDidChange(textField:)), for: .editingChanged)

和处理方法:

func textFieldDidChange(textField: UITextField) { 

}

Swift 4.0

textField.addTarget(self, action: #selector(ViewController.textFieldDidChange(_:)),
                          for: UIControlEvents.editingChanged)

和处理方法:

@objc func textFieldDidChange(_ textField: UITextField) {

}

Answer 4

到目前为止我处理它的方式:in UITextFieldDelegate

func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool
{
    // text hasn't changed yet, you have to compute the text AFTER the edit yourself
    let updatedString = (textField.text as NSString?)?.stringByReplacingCharactersInRange(range, withString: string)

    // do whatever you need with this updated string (your code)


    // always return true so that changes propagate
    return true
}

Swift4版本

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    let updatedString = (textField.text as NSString?)?.replacingCharacters(in: range, with: string)
    return true
}

Answer 5

斯威夫特3

 textField.addTarget(self, action: #selector(ViewController.textFieldDidChange(sender:)), for: UIControlEvents.editingChanged)

Answer 6

Swift 3.0.1+(其他一些swift 3.0答案不是最新的)

textField.addTarget(self, action: #selector(ViewController.textFieldDidChange(_:)),
                          for: UIControlEvents.editingChanged)

func textFieldDidChange(_ textField: UITextField) {

}

Answer 7

现在有一个 UITextField 委托方法可用于 iOS13+

optional func textFieldDidChangeSelection(_ textField: UITextField)

Answer 8

您可以使用 UITextFieldDelegate 中的此委托方法。它会随着每个角色的变化而触发。

(Objective C) textField:shouldChangeCharactersInRange:replacementString:
(Swift) textField(_:shouldChangeCharactersInRange:replacementString:)

但是，这仅在进行更改之前触发（实际上，只有在您从此处返回 true 时才会进行更改）。

Answer 9

textField(_:shouldChangeCharactersIn:replacementString :)在Xcode 8,Swift 3中为我工作,如果你想检查每一个按键.

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

    // Whatever code you want to run here.
    // Keep in mind that the textfield hasn't yet been updated,
    // so use 'string' instead of 'textField.text' if you want to
    // access the string the textfield will have after a user presses a key

    var statusText = self.status.text
    var usernameText = self.username.text

    switch textField{
    case self.status:
        statusText = string
    case self.username:
        usernameText = string
    default:
        break
    }

    if statusText == "" && usernameText == "" {
        self.topRightButton.enabled = false
    } else {   
        self.topRightButton.enabled = true
    }

    //Return false if you don't want the textfield to be updated
    return true
}

Answer 10

斯威夫特4

符合UITextFieldDelegate.

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    // figure out what the new string will be after the pending edit
    let updatedString = (textField.text as NSString?)?.replacingCharacters(in: range, with: string)

    // Do whatever you want here


    // Return true so that the change happens
    return true
}