Implement gRPC in an iOS React Native app

问题

As described in this issue, we can't implement a gRPC client using the Node implementation because "RN is not pure Node".

So I started working on an Objective-C implementation using the Native Modules.

[service postWithRequest:request handler:^(RequestConfirmation * _Nullable response, NSError * _Nullable error) {
    if (response) {
        // This prints correctly in my JS console
        RCTLogInfo(@"%@", response.message);

        // This generates an error, see below
        resolve(response);

        // This works
        NSDictionary *formattedResponse = @{
            @"id": response.id_p,
            @"message": response.message
        };
        resolve(formattedResponse);
    } else {
        reject(@"error", @"An error occurred while saving", error);
    }
}];

Error :

RCTJSONStringify() encountered the following error: Invalid type in JSON write (RequestConfirmation)

As you can see the problem is with the resolve method. I suppose React does not find any way to convert my proto message to JSON.

How can I keep the response as is and pass it to the resolve method ? Then I can decode it in my JS code.

Thanks.

EDIT 1 :

RequestConfirmation is defined in my proto file like this :

message RequestConfirmation {
    string id = 1;
    string message = 2;
}

And then it is generated in Objective-C :

@interface RequestConfirmation : GPBMessage

@property(nonatomic, readwrite, copy, null_resettable) NSString *id_p;

@property(nonatomic, readwrite, copy, null_resettable) NSString *message;

@end

回答1:

Maybe the following is a potential solution for this.

Improbable Engineering have coded:

• grpc-web - Typescript/Javascript, browser or NodeJS!

Aside from the unfortunate naming, this appears not to be a mere fork of the official, C++-using, grpc-web project).

Quoting the Improbable project's own grpc-web-client page:

This library is intended for both JavaScript and TypeScript usage from either a browser or Node.js

The possible benefits of Improbable's version seem to be: 1. It doesn't appear to use native code (i.e. no C/C++/Java) 2. It can generate Typescript (therefore JavaScript) for Node.JS

So, maybe, we could get GRPC-on-RN working, when point No. 2 is coupled with a NodeJS-on-RN project such as rn-nodeify.

Please provide feedback, if you have any success with this.

来源：https://stackoverflow.com/questions/44962290/implement-grpc-in-an-ios-react-native-app