Signal is already bound to key path

Question

I'm quite new to RAC and run into the following issue.

I bind a NSArray property of object to a signal that fetches some json payload from a webservice like this:

- (void)updateRandomUserData
{
    RAC(self, users) = [[[self fetchRandomUserData] map:^(NSDictionary *json) {
        NSMutableArray *randomUsers = [NSMutableArray array];
        for (NSDictionary *dict in json[@"data"]) {
            BKRandomUser *randomUser = [MTLJSONAdapter modelOfClass:[BKRandomUser class] fromJSONDictionary:dict error:nil];
            [randomUsers addObject:randomUser];
        }
        return randomUsers;
    }] catch:^(NSError *error) {
        return [RACSignal return:@[]];
    }];
}

I see this is working as intented when I call that from the viewDidLoad of the proper view controller:

[[[RACObserve(self.randomUserManager, users) deliverOn:RACScheduler.mainThreadScheduler] filter:^BOOL(NSArray *users) {
            return users.count > 0;
        }] subscribeNext:^(NSArray *newUsers) {
            @strongify(self);
            self.loggedOutDataSource.items = newUsers;
            if (self.refreshControl.refreshing) {
                [self.refreshControl endRefreshing];
            }
            [self.tableView reloadData];
        }];

        [self.randomUserManager updateRandomUserData];

However when I want to call that [self.randomUserManager reloadManager] at a later point during the view controller's lifecycle I get a crash saying:

* Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Signal name: [[[+createSignal:] -doError:] -map:] -catch: is already bound to key path "users" on object , adding signal name: [[[+createSignal:] -doError:] -map:] -catch: is undefined behavior'

I assume the problem is that when calling [self.randomUserManager updateRandomUserData] it's trying to bind the NSArray property again.

So I guess the question is how can I avoid binding the property several times but still be able to use the signal that was created to call the method?

Answer 1

The problem was that I did not call [subscriber setCompleted] to terminate the subscription.

Answer 2

try to unsubscribe before calling selector:

- (void)updateRandomUserData
{
    RAC(self, users) = [[[[self fetchRandomUserData] map:^(NSDictionary *json) {
       NSMutableArray *randomUsers = [NSMutableArray array];
       for (NSDictionary *dict in json[@"data"]) {
            BKRandomUser *randomUser = [MTLJSONAdapter modelOfClass:[BKRandomUser class] fromJSONDictionary:dict error:nil];
                [randomUsers addObject:randomUser];
            }
        return randomUsers;
    }] catch:^(NSError *error) {
        return [RACSignal return:@[]];
    }] takeUntil:[self rac_signalForSelector:@selector(updateRandomUserData)]];
}