Removing nested subscribeNext in reactive pipeline

Question

I am trying to construct a reactive pipeline where a change in some input signals will trigger off an asynchronous web api request. But I do not need to perform anything in the subscribeNext block of the web api.

This is how it looks:

RACSignal *inputChanged = [[RACSignal merge:@[ RACObserve(self, input1), RACObserve(self, input2) ]] throttle:0.5];

@weakify(self)
[[[inputChanged
  subscribeNext:^(id x) {
      @strongify(self)
      [[self asyncWebAPI]
       subscribeNext:^(id x) {
       }];
  }];

This works. But it isn't elegant because of the nested subscribeNext: and the second subscribeNext is just to make the asyncWebAPI a hot signal.

Is there a better way to construct this pipeline?

Answer 1

Check out -flattenMap:. For example:

[[inputChanged
    flattenMap:^(id _) {
        @strongify(self);
        return [self asyncWebAPI];
    }]
    subscribeNext:^(id x) {
        // Do stuff
    }];