ios - what is the extension of an executable file in an xcode project -

i downloaded apple researchkit last month , run sample. worked , every thing fine. week tried run , had build failed , error need have appledoc:

error: appledoc required building researchkit's documentation. see http://appledoc.gentlebytes.com

i did research , found page

 [1]: https://github.com/tomaz/appledoc#quick-install 

i downloaded project , built , found

build directory.

but, didn't know executable file in directory , how can add path. can me ? lot.

i had same error message when opened working researchkit project stored in dropbox on different computer 1 created on. noticed there file called "doc" in target section of researchkit.xcodeproj. deleting file resolved problem. have no idea how "doc" file got there in first place, i've duplicated problem (and solution) since.