Brainstorming better subscribers for ReactiveCocoa 3.0. See https://github.com/ReactiveCocoa/ReactiveCocoa/pull/1308.

gistfile1.m

RACSignal *signal = [RACSignal create:^(id<RACSubscriber> subscriber) {
	for (NSUInteger i = 0; !subscriber.disposable.disposed; i++) {
		[subscriber sendNext:@(i)];
	}
}];

gistfile2.m

// Instead of the current -subscribe… methods, this makes it clearer that “connection”
// can have side effects, and that the connection is _not_ the same as the signal
// itself (e.g., signals never start or stop, only connections)
RACDisposable *disposable = [signal connect:[RACSubscriber subscriberWithNextHandler:^(id x) {
	// …
} errorHandler:^(NSError *error) {
	// …
} completedHandler:^{
	// …
}]];

[disposable dispose];

gistfile3.m

// Ensures that events are always dequeued on the main thread, possibly after a hop.
RACSubscriber *multicastingSubscriber = [[RACSubscriber alloc] initWithScheduler:RACScheduler.mainThreadScheduler];
[multicastingSubscriber addNextHandler:^(id x) {
	// Thing A
}];

[multicastingSubscriber addNextHandler:^(id x) {
	// Thing B
}];

[signal connect:multicastingSubscriber];

// Forward events to another subscriber, without connecting to the original
// source again.
[multicastingSubscriber.events connect:anotherSubscriber];

gistfile4.m

RACSubscriber *multiplexingSubscriber = [RACSubscriber subscriberWithNextHandler:^(id x) {
	// …
} errorHandler:nil completedHandler:nil];

[signalA connect:multiplexingSubscriber];
[signalB connect:multiplexingSubscriber];