gRPC Objective-C library now provides the option to use Apple's CFStream API (rather than TCP sockets) for networking. Using CFStream resolves a bunch of network connectivity transition issues (see the doc for more information).
CFStream integration is now in experimental state. You will need explicit opt-in to use it to get the benefits of resolving the issues above. We expect to make CFStream the default networking interface that gRPC uses when it is ready for production.
As of v1.21.0, CFStream integration is now the default networking stack being used by gRPC Objective-C on iOS layer. You get to use it automatically without special configuration needed. See below on how to disable CFStream in case of problem.
If you use gRPC Objective-C library on iOS, CFStream is on automatically. If you use it on other platforms, you can turn it on with macro GRPC_CFSTREAM=1
for the pod ‘gRPC-Core’ and ‘gRPC’. In case of problem and you want to disable CFStream on iOS, you can set environment variable “grpc_cfstream=0”.