The following requirements must be met for Apple device running iOS/iPadOS (ie. iPhone and iPad) to be compliant:
1) When it comes to iOS/iPadOS version, Apple supports only the latest version and occasionally the previous version for a short period to allow users time to update. Versions that are no longer sported, are no longer getting security patches and vulnerable to exploits. Unsupported versions will be considered compliant only for 6 months following the release of the last security patch, providing that last patch was installed on the device.