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
Following are the steps for solved above issue:
Search launchd.conf file in your mac
If not found then create from Terminal with help of command
~ user$ sudo touch /etc/launchd.conf
Terminal will ask you machine password
Then Open created file with help of command for EDIT, if terminal give you error as permission failed
~ user$ sudo /Applications/TextEdit.app/Contents/MacOS/TextEdit /etc/launchd.conf
Open file manually from /etc/launchd.conf (Shift+cmd+g) and enter /etc/ (TextEdit software)
In file "DYLD_INSERT_LIBRARIES" flag replace with "ZZ" and save it.
Restart your machine.
Xcode will defiantly works.