Testing RAC by writing a socket abstraction on top of it with AsyncSocket

ExampleUsage.m

[[[TCRACSocket connectTo:@"localhost" port:1236] selectMany:^id<RACSubscribable>(id x) {
    return [x lines];
}] subscribeNext:^(id x) {
    self.text.text = x;
} error:^(NSError *error) {
    NSLog(@"Failure: %@", error);
    exit(0);
}];

TCRACSocket.h

#import <Foundation/Foundation.h>
#import <ReactiveCocoa/ReactiveCocoa.h>
#import <AsyncSocket.h>

@interface TCRACSocket : NSObject
+(RACSubscribable*)connectTo:(NSString*)host port:(int)port;
@property(strong,readonly) AsyncSocket *sock;

-(RACSubscribable*)lines;
@end

TCRACSocket.m

#import "TCRACSocket.h"
#import <AsyncSocket.h>

@interface TCRACSocket ()
@property(strong,readwrite) AsyncSocket *sock;
@property(strong) id<RACSubscriber> sub;
@end

@implementation TCRACSocket {
    NSMutableArray *_readers;
}
+(RACSubscribable*)connectTo:(NSString*)host port:(int)port;
{
    return [RACSubscribable createSubscribable:^RACDisposable *(id<RACSubscriber> subscriber) {
        TCRACSocket *wrapper = [TCRACSocket new];
        NSError *err = nil;
        wrapper.sub = subscriber;
        if(![wrapper.sock connectToHost:host onPort:port error:&err])
            [subscriber sendError:err];
        return nil;
    }];
}
-(id)init;
{
    if (!(self = [super init]))
        return nil;
    
    _sock = [[AsyncSocket alloc] initWithDelegate:self];
    
    return self;
}
- (void)onSocket:(AsyncSocket *)sock willDisconnectWithError:(NSError *)err;
{
    [_sub sendError:err];
    for(id<RACSubscriber> sub in _readers)
        [sub sendError:err];
}
- (void)onSocket:(AsyncSocket *)sock didConnectToHost:(NSString *)host port:(UInt16)port;
{
    [_sub sendNext:self];
    [_sub sendCompleted];
    [self.sock readDataToData:[AsyncSocket LFData] withTimeout:-1 tag:0];
}
- (void)onSocket:(AsyncSocket *)sock didReadData:(NSData *)data withTag:(long)tag
{
    NSString *s = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
    for(id<RACSubscriber> sub in _readers)
        [sub sendNext:s];
    [self.sock readDataToData:[AsyncSocket LFData] withTimeout:-1 tag:0];
}

-(RACSubscribable*)lines;
{
    return [RACSubscribable createSubscribable:^RACDisposable *(id<RACSubscriber> subscriber) {
        if (!_readers) {
            _readers = [NSMutableArray new];
        }
        [_readers addObject:subscriber];
        return [RACDisposable disposableWithBlock:^{
            [_readers removeObject:subscriber];
            if (_readers.count == 0) {
                _readers = nil;
            }
        }];
    }];
}
@end