Изменение размера шрифта UITextField в UIAlertView

Кто-нибудь знает, как изменить размер шрифта UITextField в UIAlertView? Ниже приведен мой код...

- (void) editTitle
{
    NSString *string = kLocalizedString(@"Edit Title");

    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:nil
                                                message:string
                                               delegate:self
                                      cancelButtonTitle:@"Cancel"
                                      otherButtonTitles:@"OK", nil];

    alert.alertViewStyle = UIAlertViewStylePlainTextInput;
    UITextField *textField = [alert textFieldAtIndex:0];
    if (!self.title) {
        textField.text = nil;
    }
    else {
        textField.text = self.title;
    }

    textField.clearsOnBeginEditing = NO;
    textField.clearButtonMode = UITextFieldViewModeAlways;
    textField.autocapitalizationType = UITextAutocapitalizationTypeWords;
    textField.clearsContextBeforeDrawing = NO;

    // These statements have no effect on the size of the text field's font
    textField.font = [UIFont systemFontOfSize:16.0];
    NSDictionary *attributes = @{
                NSFontAttributeName: [UIFont systemFontOfSize:16.0]}; 
    textField.typingAttributes = attributes;

    [alert show];
}