Hello,
after upgrading from High Sierra to Mojave Xcode (both versions, 10.1 and 10.2.1) crash on startup with the following message:
Library not loaded: @rpath/libswiftAVFoundation.dylib
Referenced from: /Applications/Xcode.app/Contents/MacOS/Xcode
Reason: image not found
before upgrading to Mojave it was possible to start 10.1, but had no luck starting apps on devices with iOS 12.3.1