I have Xcode 8.3 and Xcode 9.1, I came to this post to find a solution to missing simulators after forced upgrade to 9.1...
I was about to do the suggestion to remove the entire DerivedData directory, lucky closing Xcode 9.1 and restarting it worked. Moreover, I had to close all simulator(s).
1) Delete derived data,
Xcode-> Preferences -> Locations and select arrow symbol just before Advance button -> select all files and delete.
2) Quite Xcode
3) Quite Xcode from Dock
4) Open Xcode again.
Having a higher deployment target than what is installed on your simualtors also causes this.
I have Xcode 8.3 and Xcode 9.1, I came to this post to find a solution to missing simulators after forced upgrade to 9.1...
I was about to do the suggestion to remove the entire DerivedData directory, lucky closing Xcode 9.1 and restarting it worked. Moreover, I had to close all simulator(s).
I had to rebuild app apps on simulator again.
When my xcode updated to 9.4 I face the same problem at first time. After force quit and start again solve the problem for me.
If you upgraded Xcode then follow the steps
:-) Hope this will help you.
You may have removed iOS Simulators when you cleaned up disk space. I think I may have used DaisyDisk to remove files when I ran out of space.
You can re-add simulators using the Devices & Simulators window. (Shift + Command + 2)
This may happen due to multiple Xcode installed on machine or might be the deployment target is higher than the simulator OS version.
In order to resolve this navigate to following location : Xcode > Preference > location > comindline Tool > change the xcode version
and decrease the deployment target.