Detecting a change to text in UITextfield

Question

I would like to be able to detect if some text is changed in a UITextField so that I can then enable a UIButton to save the changes.

Answer 1

For that, first you need to have your textfield have it delegate reference assigned. And the delgate, should preferably be, the vew controller which is the files owner of the view. Which goes like

myTextField.delegate = myViewControllerReferenceVariable

And in your viewController interface, tell you will be implementing UITextFieldDelegate by

@interface MyViewController:UIViewController

And in your view controller implementation override

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string

So the code will look like

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
     {
        text = [textfield.text stringByReplacingCharactersInRange:range withString:string];
        if (textfield == refToTextFieldYouWantToCheck) {
            if ( ! [textToCheck isEqualToString:text] ) {
               [theButtonRef setEnabled:YES];
            } 
         }
           return YES; //If you don't your textfield won't get any text in it
      }

You can also subscribe to notification which is sort of messy IMHO You can find how to do it here.