Use Xcode 7 with iOS Device running iOS 10

Standard procedure that has worked in the past is

1) Install shiny new beta Xcode on your Mac and shiny new beta iOS on your device

2) Run new Xcode and connect your device

3) Wait until new Xcode has finished installing the developer disk image (green light in Devices window)

4) Close new Xcode and fuggedaboutit

After being "blessed" by the new Xcode, you should then be able to use the device running the new OS with the old Xcode.

Disclaimer: I have not tried this with Xcode 8 and iOS 10. But it has worked for me on all past versions.

I've used that process in the past but it didn't seem to work this time. It might be because I'm manually installing versions of Xcode (even the current one) rather than using the Mac App Store version. I found this procedure, which did allow me to build on Xcode 7 and run on iOS 10: http://stackoverflow.com/questions/37945376/how-use-xcode-7-with-ios-10

This can be a useful process because it (hopefully) lets you see how iOS 10 will deal with older apps that have not been recompiled against iOS 10. Just rebuilding with Xcode 8/iOS 10 can change the behaviour. In the past, iOS has been very good at providing backward compatibility for older apps. Today Widgets, at least in beta 1, are an example where things don't just work because the UI has changed so much.

http://stackoverflow.com/questions/37945376/how-use-xcode-7-with-ios-10