Minimum iOS Version:
The current minimum iOS version supported by ForeFlight is iOS 9.2.
New iOS Version:
February 28, 2018: Compatibility testing between ForeFlight and iOS 11.2.6 is complete and we are issuing the “all-clear” to ForeFlight customers. Feel free to update at your convenience.
Follow this link to learn how you can check which Apple iOS version you are currently running.