This issue occurs because the application version you are using does not support connectivity with Apple devices. You need to update Device Interconnectivity Services and Xiaomi Share to the latest versions. Specifically, Device Interconnectivity Services should be 16.00.50 or higher, and Xiaomi Share should be 3.3.0 or higher.
To check the version, go to [Settings] >> [Apps] >> [Manage apps] >> tap the three-dot icon at the upper right corner >> [Show all apps], then search for these two APPs in the search bar. Both APPs will receive updates through the application store over time.
Note:
The Xiaomi Interconnectivity Services APP is available for search and download in Apple’s App Store.