Unity uses the Input class to access input on all mobile devices.
iOS devices include a touchscreen keyboard. When you select editable UI(User Interface) Allows a user to interact with your application. Unity currently supports three UI systems. More info
See in Glossary elements such as Input Fields, Unity automatically activates the iOS touchscreen keyboard and handles input from it. For information on how to manually activate and configure the iOS touchscreen keyboard, refer to Mobile Keyboard.