grpc-swift/docs/client-without-codegen.md

Calling a Service Without a Generated Client

It is also possible to call gRPC services without a generated client. The models for the requests and responses are required, however.

If you are calling a service which you don't have a generated client for, you can use AnyServiceClient. For example, to call the "SayHello" RPC on the Greeter service you can do the following:

let channel = ... // get a GRPCChannel
let anyService = AnyServiceClient(channel: channel)

let sayHello = anyService.makeUnaryCall(
  path: "/helloworld.Greeter/SayHello",
  request: Helloworld_HelloRequest.with {
    $0.name = "gRPC Swift user"
  },
  responseType: Helloworld_HelloResponse.self
)

Calls for client-, server- and bidirectional-streaming are done in a similar way using makeClientStreamingCall, makeServerStreamingCall, and makeBidirectionalStreamingCall respectively.

These methods are also available on generated clients, allowing you to call methods which have been added to the service since the client was generated.