Implicit declaration of function 'LOG_OBJC_MAYBE' is invalid in C99

Step 1:
change #import "DDLog.h" to #import in file HTTPLogging.h

Step 2:
add the following macro in file HTTPLogging.h

#define HTTP_LOG_OBJC_MAYBE(async, lvl, flg, ctx, frmt, ...) \
do{ if(HTTP_LOG_ASYNC_ENABLED) LOG_MAYBE(async, lvl, flg, ctx, nil, sel_getName(_cmd), frmt, ##__VA_ARGS__); } while(0)

#define HTTP_LOG_C_MAYBE(async, lvl, flg, ctx, frmt, ...) \
do{ if(HTTP_LOG_ASYNC_ENABLED) LOG_MAYBE(async, lvl, flg, ctx, nil, __FUNCTION__, frmt, ##__VA_ARGS__); } while(0)

Step3:
replace all LOG_OBJC_MAYBE with HTTP_LOG_OBJC_MAYBE and all LOG_C_MAYBE with HTTP_LOG_C_MAYBE in file HTTPLogging.h

Hope my experience can give help.