When I try to run my app with Xcode 6 Beta 4 on the Simulator iOS 8.0 I always get this error:
Unable to boot the iOS Simulator
I am very happy that finally my issue resolved. Thanks to apple who helped me.
For those who are still looking for solution, here is the one which helped me:
Just unset DYLD_INSERT_LIBRARIES environment variable in the /etc/launchd.conf or ~/.launchd.conf file. Which you can edit by sudo vi /etc/launchd.conf command. remove the above flag save it by "ZZ" (captial Z) and reboot the system. It works like a charm.
For reference: Xcode 6 simulator, unable to boot error.