Unity TouchScreenKeyboard detect return key

Hi, I'm using TouchScreenKeyboard.Open in my Unity - iOS app and I can open the keyboard in iPad using that and enter some text and submit it when the Done button is clicked. Now the client wants to submit the text when the user clicks the Return key in the keyboard, instead of clicking the Done button. But I couldn't find a way to catch the Return key click in Unity side. I tried code like if (Input.GetKey(KeyCode.Return)) { but it never get called. Can you please tell me how to catch the keyboard keys pressed events or at least return key pressed event in Unity or in iOS side when using the unity TouchScreenKeyboard.Open. Thanks