Installation Failed "Invalid argument" when trying to run Today application extension

ios ios-app-extension xcode6.1

Check if the Bundle Identifier isn't empty in the Info.plist

ios ios-app-extension xcode6.1

Try this:

Quit Xcode
Clean out ~/Library/Developer/Xcode/DerivedData manually
rm -rf "$(getconf DARWIN_USER_CACHE_DIR)/org.llvm.clang/ModuleCache"
iOS Simulator > Reset Content and Settings

ios ios-app-extension xcode6.1

Maybe you are bundling a conflicting "contents" referenced (blue) folder.

Hint: change the name of said "contents" folder :)