RobotUI is an app that displays a UI defined by you. The UI is defined in your Arduino code and is transmitted over bluetooth to the RobotUI app.
You can then control your Arduino project with your UI. Define your buttons, checkboxes, toggles, sliders and drop downs menus.
Update the UI definition in your Arduino code and your changes will automatically be reflected in the RobotUI app while it is connected to your Arduino.
UI state is also transmitted to that app, so reconnecting to your Arduino after a long period will show the current state of your project.
There are setup guides and examples at www.bigbagofbits.com/robotui