Quickies for UITextField

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General

• Adding a decimal point to the numeric keyboard [permalink]
  Apple added a decimal pad keyboard type. As of Xcode 4.1, not exported in the UI, so you have to set it in code:

  textField.keyboardType = UIKeyboardTypeDecimalPad;
  

• Bringing up the phone keyboard [permalink]
  

      [self.nameField becomeFirstResponder];

  If you want the keyboard to animate in after your view appears, you can call this in your -viewWillAppear:

• Dismissing the on-screen keyboard [permalink]
  If you know the text field that is being edited, you can tell it to resign first responder:

  [textField resignFirstResponder];
  

  Otherwise, you can tell the enclosing view to end editing, and it'll figure out who is editing and tell them to resign:

  [self.view endEditing: YES];
  

• Getting notified of UITextField changes [permalink]
  Easiest way is to hook up the Editing Changed (NOT Value Changed) action.

• Handling keyboard return button [permalink]
  Notifications about the UITextField keyboard return button come through this delegate method. This one hides the keyboard when the return button is typed.

  - (BOOL) textFieldShouldReturn: (UITextField *) textField {
      // Dismiss the keyboard.
      [self.view endEditing:YES];
      return YES;
  }
  

• Only allowing numbers in a text field [permalink]
  Sometimes you need a more general keyboard for a numeric-only text field. You can do something like this in a delegate method:

  - (BOOL) textField: (UITextField *) textField
    shouldChangeCharactersInRange: (NSRange) range
                replacementString: (NSString *) string {
      NSString *resultingString = [textField.text stringByReplacingCharactersInRange: range
                                            withString: string];
      if (resultingString.length == 0) return YES;
      NSScanner *scanner = [NSScanner scannerWithString: resultingString];
  
      float throwaway;
      BOOL scansFloat = [scanner scanFloat: &throwaway];
      BOOL atEnd = [scanner isAtEnd];
  
      return scansFloat && atEnd;
  
  } // shouldChangedCharacersInRanges
  

  (thanks to Frank Shearer, from a SO post)

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