NSStream and Sockets, NSStreamDelegate methods not being called

Question

I've followed the guide Setting Up Socket Streams and have effectively duplicated that code in my class. No matter what I try the delegate methods just don't seem to get called.

In the header file I have (basically):

@interface myClass : NSObject <NSStreamDelegate> {
    NSInputStream *inputStream;
    NSOutputStream *outputStream;
}
- (void)connect;
@end;

The connect method:

- (void)connect {
    CFReadStreamRef readStream;
    CFWriteStreamRef writeStream;

    CFStreamCreatePairWithSocketToHost(kCFAllocatorDefault, (CFStringRef)@"host.example.com", 1234, &readStream, &writeStream);

    inputStream = (NSInputStream *)readStream;
    outputStream = (NSOutputStream *)writeStream;
    [inputStream setDelegate:self];
    [outputStream setDelegate:self];
    [inputStream scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
    [outputStream scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
    [inputStream open];
    [outputStream open];
}

Also tried using CFStreamCreatePairWithSocketToCFHost() and [NSStream getStreamsToHost:port:inputStream:outputStream: - all with exactly the same result.

I've set a breakpoint at the beginning of the connect method, stepped through every line and every pointer is valid and seems to point to the correct object.

In GDB, after the setDelegate calls, po [inputStream delegate] prints <myClass: 0x136380> as expected, so it has set the delegate correctly.

For the life of me I can't work out why it refuses to call the stream:handleEvent: method on my class:

- (void)stream:(NSStream *)aStream handleEvent:(NSStreamEvent)eventCode {
    NSLog(@"got an event");
}

Hopefully I've missed something really simple and obvious and a second pair of eyes can spot my mistake.

Thanks in advance to anyone who has the patience and taken the time to read this far!