ReactiveCocoa flattenMap not called - ios

Question

I have two data sources that are pulling in different arrays of both Contacts and Users and an aggregate Invitee datasource which is created to combine and keep references to the results of the Contacts and Users:
AddressBookDataSource:
- (RACSignal *)getContacts {
return [[[[self getContactsSignal] flattenMap:^RACStream *(NSArray *contacts) {
return contacts.rac_sequence.signal;
}]
map:^id(APContact *contact) {
return [[Contact alloc] initWithAPContact:contact];
}] collect];;
}
- (RACSignal*)getContactsSignal {
APAddressBook *addressBook = [[APAddressBook alloc] init];
addressBook.fieldsMask = APContactFieldFirstName | APContactFieldCompositeName | APContactFieldPhoto;
RACSignal *addressBookSignal = [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
[addressBook loadContacts:^(NSArray *contacts, NSError *error) {
if (error) {
[subscriber sendError:error];
} else {
[subscriber sendNext:contacts];
}
}];
return nil;
}];
return addressBookSignal;
}
ParseDataSource:
- (RACSignal *)getUsers {
return [[[[[self getUsersSignal] flattenMap:^RACStream *(NSArray *users) {
return users.rac_sequence.signal;
}] filter:^BOOL(User *user) {
return ![user.username isEqualToString:[User currentUser].username];
}] map:^id(User *user) {
return user;
}] collect];
}
- (RACSignal*)getUsersSignal {
RACSignal *getUsersSignal = [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
PFQuery *userQuery = [User query];
[userQuery findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) {
if (error) {
[subscriber sendError:error];
} else {
[subscriber sendNext:objects];
}
}];
return nil;
}];
return getUsersSignal;
}
InviteeDataSource:
- (RACSignal*)getPotentialInvitees {
ParseDataSource *parseDataSource = [[ParseDataSource alloc] init];
AddressBookDataSource *addressBookDataSource = [[AddressBookDataSource alloc] init];
return [[RACSignal concat:#[
[parseDataSource getUsers],
[addressBookDataSource getContacts]
]]
flattenMap:^RACSignal *(RACTuple *tuple) {
RACTupleUnpack(NSArray *users, NSArray *contacts) = tuple;
_contactSection.contacts = contacts;
_userSection.users = users;
return [RACSignal empty];
}];
}
The problem is that the flattenMap block never gets called, meaning the subsequent subscribers never have their subscribeNext blocks called.
Help?

Answer 1

Thanks to a twitter reply from #jspahrsummers, there were a couple things that were making this not behave as I'd like, but the root of the problem seemed to be that I was not calling -sendCompleted on the subscriber in the -getUsersSignal and -getContactsSignal.