Could not resolve external type c

Solution 1
Under the Project Target > Build Settings, change the “Debug Information Format
” from “DWARF with dSYM File
” to “DWARF
”.
Solution 2
Deployment Postprocessing = Yes (DEPLOYMENT_POSTPROCESSING=YES
)
Generate Debug Symbols = No (GCC_GENERATE_DEBUGGING_SYMBOLS=NO
)
Symbols Hidden by Default = Yes (GCC_SYMBOLS_PRIVATE_EXTERN=YES
)