How do I check when a UITextField changes?

问题:

I am trying to check when a text field changes, equivalent too the function used for textView - textViewDidChange so far I have done this:

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

Which kind of works, but the topRightButton is enabled as soon as the text field is pressed on, I want it to be enabled only when text is actually typed in?

回答1:

SWIFT

textField.addTarget(self, action: "textFieldDidChange:", forControlEvents: UIControlEvents.EditingChanged)

Then you can just call your function!

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

SWIFT 2.2

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

and

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

SWIFT 3

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

and

func textFieldDidChange(_ textField: UITextField) {  }

Swift 4

@objc func textFieldDidChange(_ textField: UITextField) {  }

OBJECTIVE-C

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

and textFieldDidChange method is

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

回答2:

You can make this connection in interface builder.

1. In your storyboard, click the assistant editor at the top of the screen (two circles in the middle).

2. Ctrl + Click on the textfield in interface builder.

3. Drag from EditingChanged to inside your view controller class in the assistant view.

4. Name your function ("textDidChange" for example) and click connect.

回答3:

Swift 3.0

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

and handle method:

func textFieldDidChange(textField: UITextField) {   }

Swift 4.0

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

and handle method:

@objc func textFieldDidChange(_ textField: UITextField) {  }

回答4:

Swift 3

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

回答5:

The way I've handled it so far : in UITextViewDelegate

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 }

回答6:

Swift 3.0.1+ (Some of the other swift 3.0 answers are not up to date)

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