Using OnlineSubsystemGoogle in iOS, GoogleExternalUI is commented

Cannot use OnlineSubsystemGoogle in iOS.
I found below code in OnlineSubsystemGoogle.cpp ( Source/Private/iOS )

//#include "OnlineExternalUIInterfaceGoogle.h"

bool FOnlineSubsystemGoogle::Init()
		//GoogleExternalUI = MakeShareable(new FOnlineExternalUIGoogle(this));

So, both of OnlineSubsystemGooglePlay and OnlineSubsystemGoogle are cannot use in iOS.
How I Google login in iOS ? I cannot found in Marketplace too. Make native plugin?

I 'm currently facing the same problem. If you have solved it, could you please leave a history?