iPad UITextField won't return

Question

Hi,

I have an UITextField inside an UITableViewCell. I want the textField to return but something goes wrong. Here's my code:

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
if (indexPath.section == 0) {
        if (indexPath.row == 0) {
            cell.selectionStyle = UITableViewCellSelectionStyleNone;
            usernameField = [[UITextField alloc] initWithFrame:CGRectMake(20, 0, cell.contentView.frame.size.width, cell.contentView.frame.size.height)];
            usernameField.adjustsFontSizeToFitWidth = YES;
            usernameField.placeholder = @"Username";
            usernameField.contentVerticalAlignment = UIControlContentVerticalAlignmentTop;
            usernameField.backgroundColor = [UIColor clearColor];
            usernameField.keyboardType = UIKeyboardTypeDefault;
            usernameField.autocapitalizationType = UITextAutocapitalizationTypeNone;
            usernameField.autocorrectionType = UITextAutocorrectionTypeNo;
            usernameField.contentVerticalAlignment = UIControlContentVerticalAlignmentCenter;
            usernameField.returnKeyType = UIReturnKeyDone;
            usernameField.delegate = self;
            usernameField.clearButtonMode = UITextFieldViewModeAlways;
            [usernameField setEnabled:YES];
            [cell addSubview:usernameField];
            [usernameField becomeFirstResponder];
            [usernameField release];            
        }
    }
}

- (BOOL)textFieldShouldReturn:(UITextField *)textField {
    [textField resignFirstResponder];
    return YES;
}

I also implemented my class to UITextFieldDelegate

Thanks!