iPhone Force Textbox Input to Upper Case

Question

How do I force characters input into a textbox on the iPhone to upper case?

Solution 1

Set autocapitalizationType to UITextAutocapitalizationTypeAllCharacters on the UITextField.

See UITextInputTraits protocol (adopted by UITextField) for more details.

Solution 2

This solution is not fully satisfying.

Even with the autocapitalizationType set to UITextAutocapitalizationTypeAllCharacters, the user can still press caps to release the caps lock. And the textField.text = [textField.text stringByReplacingCharactersInRange:range withString:[string uppercaseString]]; return NO; solution is not that great: we loose the editing point if the user edits the middle of the text (after a textField.text =, the editing cursor goes to the end of the string).

I've done a mix of the two solution and here is what I propose: set UITextAutocapitalizationTypeAllCharacters, and add the following code to the delegate of the UITextField.

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

    // Check if the added string contains lowercase characters.
    // If so, those characters are replaced by uppercase characters.
    // But this has the effect of losing the editing point
    // (only when trying to edit with lowercase characters),
    // because the text of the UITextField is modified.
    // That is why we only replace the text when this is really needed.
    NSRange lowercaseCharRange;
    lowercaseCharRange = [string rangeOfCharacterFromSet:[NSCharacterSet lowercaseLetterCharacterSet]];

    if (lowercaseCharRange.location != NSNotFound) {

        textField.text = [textField.text stringByReplacingCharactersInRange:range
                                                                 withString:[string uppercaseString]];
        return NO;
    }

    return YES;
}

Solution 3

While all the other answers do actually work (they make the input uppercase), they all have the problem that the cursor position is not retained (try inserting a character in the middle of the existing text). This apparently happens in the setter of UITextField's text property, and I have not found a way to restore it programmatically (for example, restoring the original selectedTextRange does not work).

However, the good news is, that there is a direct way to replace parts of a UITextField's (or UITextView's) text, which does not suffer from this issue:

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
    // not so easy to get an UITextRange from an NSRange...
    // thanks to Nicolas Bachschmidt (see http://stackoverflow.com/questions/9126709/create-uitextrange-from-nsrange)
    UITextPosition *beginning = textField.beginningOfDocument;
    UITextPosition *start = [textField positionFromPosition:beginning offset:range.location];
    UITextPosition *end = [textField positionFromPosition:start offset:range.length];
    UITextRange *textRange = [textField textRangeFromPosition:start toPosition:end];

    // replace the text in the range with the upper case version of the replacement string
    [textField replaceRange:textRange withText:[string uppercaseString]];

    // don't change the characters automatically
    return NO;
}

For further information on these methods, see the documentation of UITextInput.

Solution 4

This is my code, when i have 6 textFields

Hope you will get the point

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
    if (textField==self.textField6) {
        self.textField6.text = [textField.text stringByReplacingCharactersInRange:range withString:[string uppercaseString]];
        return NO;
    }
    return YES;
}

Solution 5

The simplest way would be to , implement the editing changed method of the text field and set the textfield's text value to upper case representation of the entered text

- (IBAction)TextFieldEditingChanged:(id)sender
{
    _yourTextField.text = [_yourTextField.text uppercaseString];
}

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