I successfully installed the app several times. Suddenly, I got this message "My App" exited unexpectedly, lost connection. This happens with iOS 6.x and 7 . I already tried deleting app manually from simulator, resetting, clean, quit, restart, everything ...
In the iOS Simulator menu, do "Reset Content & Settings". If that doesn't fix it, reboot your computer.
I found a "Fix" for this. After trying everything and getting the same error on "My App", I opened and tried to run "My App 2". "My App 2" ran fine, so I went back to "My App", tried again and this time everything worked fine. Crazy
rm -rf ~/Library/Developer/Xcode/DerivedData fixes the issue for me (reference: How to Empty Caches and Clean All Targets Xcode 4)