It's compatible with iPhone 4s and above, as well as Apple iPod Touch Gen 5 and above, and many other devices. Make sure to check out the Troubleshooting page to see how to connect your phone to the MiP robot at WowWee MiP Robot Troubleshooting.
If the WowWee MiP Robot is not detecting obstacles the robot may need to be restarted. For further information on this problem please refer to the troubleshooting guide located at WowWee MiP Robot Troubleshooting on the "MiP Cannot Detect Obstacles" section.
The MiP wheels might just need a regular cleaning. If you need help on removing the the tire please refer to the "MiP moves too Slowly" section in the WowWee MiP Robot troubleshooting page located at WowWee MiP Robot Troubleshooting.