Errors when building

[Myran]

Hello, first thank you for adding this to github! I am trying to build this on macos I get the following error:

[ 45%] Compiling ==> modules/firebase/admob.cpp
[ 45%] Compiling ==> modules/firebase/analytics.cpp
[ 46%] Compiling ==> modules/firebase/auth.cpp
[ 46%] Compiling ==> modules/firebase/convertor.cpp
[ 46%] Compiling ==> modules/firebase/database.cpp
In file included from modules/firebase/analytics.cpp:1:
In file included from modules/firebase/analytics.h:6:
modules/firebase/firebase.h:12:9: error: unknown type name 'id' [2]
 typedef id AppActivity;
         ^
In file included from modules/firebase/auth.cpp:1:
In file included from modules/firebase/auth.h:6:
modules/firebase/firebase.h:12:9: error: unknown type name 'id' [2]
 typedef id AppActivity;
         ^
[ 46%] Compiling ==> modules/firebase/firebase.cpp
1 error generated.
scons: *** [modules/firebase/analytics.iphone.opt.arm64.o] Error 1
1 error generated.
scons: *** [modules/firebase/auth.iphone.opt.arm64.o] Error 1
In file included from modules/firebase/convertor.cpp:1:
In file included from modules/firebase/convertor.h:6:
modules/firebase/firebase.h:12:9: error: unknown type name 'id' [2]
 typedef id AppActivity;
         ^
In file included from modules/firebase/database.cpp:1:
In file included from modules/firebase/database.h:6:
modules/firebase/firebase.h:12:9: error: unknown type name 'id' [2]
 typedef id AppActivity;
         ^
1 error generated.
scons: *** [modules/firebase/convertor.iphone.opt.arm64.o] Error 1
1 error generated.
scons: *** [modules/firebase/database.iphone.opt.arm64.o] Error 1
In file included from modules/firebase/firebase.cpp:1:
modules/firebase/firebase.h:12:9: error: unknown type name 'id' [2]
 typedef id AppActivity;
         ^
modules/firebase/firebase.cpp:40:12:{40:12-40:21}: error: cannot initialize return object of type 'AppActivity' (aka 'int') with an lvalue of type 'void *' [2]
     return _instance;
            ^~~~~~~~~
2 errors generated.
scons: *** [modules/firebase/firebase.iphone.opt.arm64.o] Error 1
scons: building terminated because of errors.

Also if you have a small example of usage that would be great to look at.