Q:

Xcode cannot run iOS simulator

Version 8.0 beta 5.
I've recently installed the above beta version of Xcode but I'm unable to run any iOS 10.0 simulators.  I've done various uninstalls on both the 8 beta and Xcode 7, clearing out directories and reboots but no success.  After reinstalling I still can't run iOS 10.0 simulators.  (I've copied the Xcode download to another machine and successfully unpacked and installed it there without any problems, so it's not a corrupt download.)
xcrun yields the following information...
09:44:13 ~ > xcrun simctl list
== Device Types ==
iPhone 4s (com.apple.CoreSimulator.SimDeviceType.iPhone-4s)
iPhone 5 (com.apple.CoreSimulator.SimDeviceType.iPhone-5)
iPhone 5s (com.apple.CoreSimulator.SimDeviceType.iPhone-5s)
:
iPad Pro (9.7-inch) (com.apple.CoreSimulator.SimDeviceType.iPad-Pro--9-7-inch-)
iPad Pro (12.9-inch) (com.apple.CoreSimulator.SimDeviceType.iPad-Pro)
Apple TV 1080p (com.apple.CoreSimulator.SimDeviceType.Apple-TV-1080p)
== Runtimes ==
iOS 8.1 (8.1 - 12B411) (com.apple.CoreSimulator.SimRuntime.iOS-8-1)
iOS 9.3 (9.3 - 13E233) (com.apple.CoreSimulator.SimRuntime.iOS-9-3)
iOS 10.0 (10.0 - 14A5335a) (com.apple.CoreSimulator.SimRuntime.iOS-10-0) (unavailable, failed to open liblaunch_sim.dylib)
tvOS 10.0 (10.0 - 14T5321a) (com.apple.CoreSimulator.SimRuntime.tvOS-10-0)
== Devices ==
-- iOS 8.1 --
-- iOS 9.3 --
-- iOS 10.0 --
-- tvOS 10.0 --
== Device Pairs ==
09:44:18 ~ >
Any help appreciated.

A:

sudo killall -9 com.apple.CoreSimulator.CoreSimulatorService

This brought my simulators back to the run menu, allowed me to add more, and my simulators actually now run again. (Xcode 10b6).
Strangely enough, seemed to clear up a system header build problem too.. now my extra system header search directory location works and no compile error indicating it can't find the files and I did not mod the project.

