ReactiveCocoa: sendNext to a subscriber in asynchronous programming - ios

Question

I am trying to use ReactiveCococa for network connection using NSInputStream & NSOutputStream . The connect code looks as follows:
-(RACSignal*) connect: (NSString *) url {
return [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> theSubscriber) {
self.subscriber = theSubscriber;
// create inputStream and outputStream, initialize and open them
[self.inputStream open]
[self.outputStream open];
}];
return nil;
}
-(void) stream:(NSStream *)aStream handleEvent:(NSStreamEvent)eventCode {
switch (eventCode) {
case NSStreamEventHasBytesAvailable:
//read from input stream
NSArray * data = read_InputStream;
[subscriber sendNext:data];
break;
}
...
}
I have to store the value of subscriber and call sendNext on it, when I receive data in the callback method.
Is there a better way to handle this in ReactiveCocoa and avoid declaring subscriber property. Besides, this will not work with multiple subscribers.

Answer 1

You can use rac_signalForSelector to turn a delegate callback method into a signal. Then you can subscribe to this signal inside createSignal's didSubscribe block. Something like this:
- (RACSignal*)connect:(NSString *)url
{
return [RACSignal createSignal:^RACDisposable*(id<RACSubscriber> theSubscriber)
{
// create inputStream and outputStream, initialize and open them
[self.inputStream open];
[self.outputStream open];
[[self rac_signalForSelector:#selector(stream:handleEvent:)
fromProtocol:#protocol(NSStreamDelegate)]
subscribeNext:^(RACTuple *tuple)
{
NSStream *aStream = (NSStream *)tuple.first;
NSStreamEvent *eventCode = (NSStreamEvent *)tuple.second;
// check eventCode here
NSArray *data = read_InputStream;
[theSubscriber sendNext:data];
}];
return nil;
}];
}
- (void)stream:(NSStream *)aStream handleEvent:(NSStreamEvent)eventCode
{
}
When using rac_signalForSelector, the signal will pass the arguments from the method through as a tuple which you can then look at to decide what action to take.
Depending on what you're trying to achieve here, there are probably more elegant reactive solutions, but rac_signalForSelector at least solves the problem of needing the subscriber property.