Use Older Versions of Xcode After Updating Your Phone
After updating your iPhone or iPad to the latest version of iOS, you may find yourself unable to build and run from your current version of Xcode and upgrading to a newer version may not be an option for the time being. One simple workaround is to download the latest version of Xcode and symlink the device support that is missing like this:
sudo ln -s \
/Applications/Xcode-10.2.app/Contents/Developer/\Platforms/iPhoneOS.platform/DeviceSupport/12.2\ \(16E226\)/ \
/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/DeviceSupport/
Theoretically this is an unsupported configuration, however I've never had a problem when I've done this and it's kept me able to build and run to a device while I wrap up what I'm currently working on or while someone else is updating our project to the latest version of Xcode/Swift.