Any differences between proto2 and proto3 generated code are highlighted. You should read the proto2 language guide and/or proto3 language guide before reading this document. Compiler invocation The protocol buffer compiler produces Objective-C output when invoked with the --objc_out= command-line flag. The parameter to the --objc_out= option is the directory where you want the compiler to write your Objective-C output. The compiler creates a header file and an implementation file for each .
