I am currently running 2 versions of xcode. I recently upgraded from 9.3 to 9.4.1 and also xcode 10 beta 6 on High Sierra v.10.13.6. The simulators seem to work fine in xcode 10 beta 6 but are completely missing from 9.4.1 I have downloaded and installed additional simulators which show up in the simulators window list, however they are not added to the drop downs in the main project window and the devices list remains empty. I wondered if its simply that I have messed up something in the installation. I have tried to remove everything and reinstall and got the same problem.
Any advice would be great. If anyone who is also running two versions could recommend also optimum set up with installation etc. I can post more detail as required. I have added screen shots please follow the links.
[main nav - generic iOS device][1]
[empty devices panel][2]
[simulators panel][3]
[1]: https://i.stack.imgur.com/4qU4M.png
[2]: https://i.stack.imgur.com/SVLo0.png
[3]: https://i.stack.imgur.com/vavl1.png
I had a similar issue. If I created a new account on the same system that new account did not have the same issues. This lead me to believe it was a user preferences issue.
Some of the advice for fixing this involves deleting all Xcode files and re-installing from scratch. Try the solution below to see if it works for you since it’s much faster and less work.
You can see from the attached screen shot there is a device_set.plist file. Deleting this file alone doesn’t help so delete the entire directory it’s inside of.
Once downloaded you should see all of your simulators showing up. It seems to be the process of downloading a new simulator rebuilds the list of installed simulators.
Note I tried downloading a new simulator w/out throwing away the above directory to see if this would rebuild the list of simulators but it did not work.