Okay, so I'm trying to work on my app here and I'm trying to go to my Storyboard. Everytime I tap on the .Storyboard file, Xcode says "Application is not responding" and it quits. This issue just started happening last night(after installing OS X El Capitan beta 6). I'm not sure what's going on with this. Ran in with this with Xcode 6.4 and Xcode 7 beta 4.
UPDATE : A look on the developer forums shows that this issue has been happening for everyone. It seems that OS X El Capitan beta 6 breaks both versions of Xcode. Ugh. Now we wait for a new build of OS X or a new build of Xcode.
Thanks to lembacon shared a temporary workaround. (Applies to Xcode 7 beta 4 on OS X El Capitan Developer Beta 6)
Open your Terminal:
cd /Applications/Xcode-beta.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator.sdk/usr/lib
sudo mv dyld_sim dyld_sim.orig
cd /Applications/Xcode-beta.app/Contents/Developer/Platforms/WatchSimulator.platform/Developer/SDKs/WatchSimulator.sdk/usr/lib
sudo mv dyld_sim dyld_sim.orig
For XCode 6:
cd /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator.sdk/usr/lib
sudo mv dyld_sim dyld_sim.orig