Xcode not supported for iOS 11.3 by Xcode 9.2 needed 9.3
Another option is to download the 11.3 device support at:
iOS 11.3 (15E217)
And don't forget to remove "(15E217)" from folder name, so it became "11.3". Restart Xcode afterwards.
Where to paste it according to comment of EdwardM
For those that don't know where to paste the contents of the zipped file. Find your Applications icon in the dock, right-click, "Open Applications". The folder will open in Finder. Right-click Xcode > Show Package Contents. Then go to Developer > Platforms > iPhoneOS.platform > DeviceSupport
I have the same problem, OS Sierra trying to run iPhone SE with 10.3 using Xcode 9.2 and I don't have the resources to update to High Sierra and Xcode 9.3.
Solution:
- Find your friends who have Xcode 9.3
- Ask them to right click on Xcode, Show Package Contents then navigate to
Contents/Developer/Platforms/iPhoneOS.platform/DeviceSupport/11.3 (15E217) - Copy the
11.3 (15E217)folder to your old Xcode (9.2) with the same file hierarchy
Now you have Xcode 9.2 with iOS 11.3.