RACMulticastConnection and error handling

[raduraducu]

Hello, Using RACMulticastConnection it's quite easy to cache the result of a network request. However I'm having trouble in handling gracefully the following scenario: If the signal completes with error the first new subscription should trigger again the signal, all this in a thread safe manner.

Thanks.

[erichoracek]

Hi @raduraducu—it sounds like you may want something like shareWhileActive. It isn't included as a core operator in ReactiveObjC, but should give you similar behavior. It is available in this gist https://gist.github.com/jaredru/5540a15c5a1bdcc31787.

In the scenario you've described, this will have the behavior of interrupting all subscriptions when an error occurs. However, if a new subscription occurs following the error, the request will be retried.

[raduraducu]

I've looked at shareWhileActive and it does solve half of the problem. What I want to achieve is something like this:

    __weak typeof(self) welf = self;
    return [[[[RACSignal zip:@[RACObserve(self, completeResult), RACObserve(self, completing)]]
            flattenMap:^id(RACTuple *value) {
                __strong typeof(welf) swelf = welf;
                BOOL completing = [value.second boolValue];
                if (completing) {
                    return [RACObserve(swelf, completeResult) skip:1];
                }
                else {
                    if (!self.completeResult || [self.completeResult isKindOfClass:NSError.class]) {
                        [self completeAgain];
                        return [RACObserve(swelf, completeResult) skip:1];
                    }
                    else {
                        return RACObserve(swelf, completeResult);
                    }
                }
            }] subscribeOn:[RACScheduler mainThreadScheduler]] take:1];

The setting of completing and completeResult also happens on the same (main) scheduler to take care of synchronization issues. Can this be done more nicely?