I want to be clear: this issue is specifically about copying files from DeviceSupport.
Discussion about what should or does work is a separate issue, and I encourage you to file feedback if you find any limitations that don't meet your expectation.
We want to run the app on ios17 devices with lower versions of xcode, but it is strange that the iOS DeviceSupport in xcode15 is only up to 16.4, not 17. I don't understand how xcode15 can run the app on iOS17 devices
Because the way Xcode 15 beta talks to devices isn't represented in the DeviceSupport folder, because:
As the system evolves, any expectations for "how things work" could be made invalid, and this appears to be the case here.
There is quite a popular gist that people have updated for about 7 years on how to do this. It's not unusual to do.
I understand. An undocumented process happened to work (yes, for a long time), and now it doesn't. That is the nature of undocumented processes: they are subject to change, and can break things that rely on them.
Flutter is complaining about not being able to find support for iOS 17.
Sounds like Flutter may need to update their assumptions about how the system works. (I don't know why Flutter relies on that folder; that's a question for Flutter.)