I recently built an (universal) app for iOS in XCode 11.7 with deployment target set to iOS 10.0 (as per the Build Settings tab in XCode). Then I deployed that app to Testflight and was able to download and use it on a newer iPhone with the latest iOS.
However, when I tried to testflight it on my other iDevice (and old iPad 4th Gen that only runs iOS 10.3), Testflight told me that the app is only compatible with iOS 12.1 or higher. However, I've recently tested another app on Testflight built with (as far as I can tell) the exact same build settings using same MacBook and the same XCode, and that app installed on my iPad via Testflight without problems.
It sounds like the problem in App not compatible on iPhone 4s and 5 in Testflight and related posts, but my settings for "Build Active Architecture Only" are already set to "No" for Release.
I've already checked the Apple Compatiblity Matrix https://developer.apple.com/library/archive/documentation/DeviceInformation/Reference/iOSDeviceCompatibility/DeviceCompatibilityMatrix/DeviceCompatibilityMatrix.html but I am not using any special features.
There are only few things left I can think of
- I implicitly (and without meaning to) use some feature of the newer iPhones that are not included in iOS 12.1 or below
- I checked in the appstore that the app contains "medical information" (it's just anatomy drawings for students), so maybe this triggered an implicit requirement of Apple Health Kit (which does not run on iPad 4t Gen). This seems unlikely, however, as I only stated this in the App Store listing, not in XCode.
- Somewhere in the settings, there is still one remaining switch left to "only support iOS 12.1 or higher" and I just have not found it, If so, please point out where that might be
- The app that successfully installed on Testflight is an update for an older app that was published in late 2019, so maybe Apple forces new Apps to require iOS 12.1 or higher (since all apps have to be built against SDK 12.1 now) regardless of built settings, but updates for already existing apps are still allowed to run on lower iOS versions. Is this the case?
Or am I missing something entirely different?
