[[NSNotificationCenter defaultCenter] addObserver:self 
selector:@selector(didChangeTextViewText:) 
name:UITextFieldTextDidChangeNotification object:nil];



- (void) didChangeTextViewText {
 //do something
}

Swift 4版本

使用键值观察 通知对象对其他对象属性的更改。

var textFieldObserver: NSKeyValueObservation?

textFieldObserver = yourTextField.observe(\.text, options: [.new, .old]) { [weak self] (object, changeValue) in
  guard let strongSelf = self else { return }
  print(changeValue)
}

从正确的方法做uitextfield文本更改回调:

我捕获发送到UITextField控件的字符，就像这样:

// Add a "textFieldDidChange" notification method to the text field control.

在objective - c中:

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

迅速:

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

然后在textFieldDidChange方法中，您可以检查textField的内容，并根据需要重新加载您的表视图。

你可以使用它并将calculateAndUpdateTextFields作为你的选择器。

从iOS 14开始，不需要创建选择器，你可以通过一个闭包来传递一个UIAction:

let editingChanged = UIAction { _ in
    // Do something when text changes...
}
myTextField.addAction(editingChanged, for: .editingChanged)

Swift测试版本:

//Somewhere in your UIViewController, like viewDidLoad(){ ... }
self.textField.addTarget(
        self, 
        action: #selector(SearchViewController.textFieldDidChange(_:)),
        forControlEvents: UIControlEvents.EditingChanged
)

参数解释道:

self.textField //-> A UITextField defined somewhere in your UIViewController
self //-> UIViewController
.textFieldDidChange(_:) //-> Can be named anyway you like, as long as it is defined in your UIViewController

然后在你的UIViewController中添加你上面创建的方法:

//Gets called everytime the text changes in the textfield.
func textFieldDidChange(textField: UITextField){

    print("Text changed: " + textField.text!)

}

斯威夫特3.1:

选择器:类名。MethodName

  cell.lblItem.addTarget(self, action: #selector(NewListScreen.fieldChanged(textfieldChange:)), for: .editingChanged)

  func fieldChanged(textfieldChange: UITextField){

    }