Primitive example of gRPC Swift integration

Server

GroceryListService The server is just a primitive gRPC driven web-server developed in Swift. It has single request which just replay with hardcoded list of items.

Build server:

# macOS
$ cd GroceryListService
$ swift build && swift run

Both client and server build on SwiftNIO based framework grpc-swift

Client

GroceryListClient The client is extremly simple iOS 13 app developed in Swift using UIKit+Combine and MVVM pattern.

Motivation

I just was wondering how gRPC stack works in Swift and how convinient to integrate it. Hope someone will find it useful.

Brief description of .proto compilation process

First of all install protoc compliator.

$ brew install protobuf

Clone grpc-swift repo in order to achieve plugins for swift files compilation. Then build them and install.

# in grpc-swift directory
$ make plugins
$ sudo cp protoc-gen-swift protoc-gen-grpc-swift /usr/local/bin

Now we can complie .proto files

$ protoc <your proto> \ 
    --swift_out=. \
    --grpc-swift_opt=Client=true,Server=false \
    --grpc-swift_out=. # output directory

Few notes: --swift_out= - This option in charge of .pb.swift files which contains structures representing protobuf message objects.

--grpc-swift_opt= - This option in charge of options for compilation of .grpc.swift files which contains protocols of Client-Server communication. --grpc-swift_out= - Output directory for these files

Now you may use them for build gRPC client or server in Swift. For more details see grpc-swift docs or GroceryListClient/GroceryListService source files.

Author

Mikhail Kuzmin