Set Max Character Length UITextField (works with Japanese input method)

gistfile1.m

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

#define MAXLENGTH 3

- (IBAction)editingChanged:(id)sender
{
    UITextField *textField = sender;
    
    UITextRange *textRange = textField.markedTextRange;
    
    if (!textRange.start || !textRange.end) {
        if (textField.text.length > MAXLENGTH) {
            textField.text = [textField.text substringToIndex:MAXLENGTH];
        }
    }
}