Getting the Value of a UITextField as keystrokes are entered?

Question

Let's say I have the following code:

IBOutlet UITextField* nameTextField;
IBOutlet UILabel* greetingLabel;

I'd like the greetingLabel to read "Hello [nameTextField]" as soon as the user presses any key.

What I need basically is the iPhone equivalent of the Cocoa delegate method controlTextDidChange.

The textField:shouldChangeCharactersInRange: delegate method is called each time a keystroke occurs:

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

The string argument returns the character that is pressed. The actual textField's value (nameTextField.text) remains blank however.

What am I missing here? (I'd like nameTextField to reflect the exact string that the user has entered so far).

score 198 · Accepted Answer · answered Dec 23 '08 at 10:26

198

It turns out, the easiest way to do this is using Interface Builder:

Add a IBAction (to the ViewController, say, as in this case)
Ctrl-Click (or right click) on the UITextField in Interface Builder
Connect the "Editing Changed" event to the File's Owner's IBAction added in the first step.

Works like a charm :) (I can't believe I spent numerous days on this, and to realize now that the solution was much simpler than I'd thought :P)

answered Dec 23 '08 at 10:26

Debajit

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Thanks! I'd been using "Value Changed" like you'd use with a UISlider, etc. Interesting that they'd have two events which seem to have the same behavior. – wjl Aug 03 '11 at 22:42
1

For some reason I still wanted a programatic way to do this... but I gave in... This method Rocks! Thankyou for sharing... I had seen it before but after days of coding my brain is no longer functioning hehe. – Albert Renshaw Dec 06 '12 at 05:31
9

@AlbertRenshaw But you can do this in a programatic way ;) Just perform `[textField addTarget:self action:@selector(textFieldEditingChanged:) forControlEvents:UIControlEventEditingChanged]` ;). – Nat Jun 12 '15 at 10:52

score 102 · Answer 2 · answered Dec 23 '08 at 08:19

you could register an action for the event UIControlEventEditingChanges on the text field:

[nameTextField addTarget:self action:@selector(updateLabelUsingContentsOfTextField:) forControlEvents:UIControlEventEditingChanged];

...

// TODO: error checking

- (void)updateLabelUsingContentsOfTextField:(id)sender {

    greetingLabel.text = [NSString stringWithFormat:@"Hello %@", ((UITextField *)sender).text];

}

Is there a way to specify this using Interface Builder? – Debajit Dec 23 '08 at 08:24 — Debajit, Dec 23 '08 at 08:24

score 11 · Answer 3 · edited Nov 22 '14 at 19:18

11

UITextField has a notification UITextFieldTextDidChange which will be fired every time the text changes if you register for it. Just register for that notification and in the method called by the notification, change the label's text.

To add to this, the object passed to your notification handler will have the text of the UITextField.

Hope that helps.

edited Nov 22 '14 at 19:18

rihekopo

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answered Dec 23 '08 at 09:34

lostInTransit

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Getting the Value of a UITextField as keystrokes are entered?

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