You should now be able to connect an iOS application to an IoT device and use the IBM Watson IoT™ Platform.

You know how to connect to a robot that is connected to the Raspberry Pi.

To enhance your robot, you might want to add new functions and use various ASCII commands that are documented in the iRobot Create2 manual.

For example, this is the command used to dock the iRobot:
check the force dock command: 143

See GitHub for the Software Development Kit and examples.