Good Example of network-based NSStreams on a Separate Thread? - ios

Question

Does anyone know of a simple example that creates (network-based) NSStreams on a separate thread?
What I am actually trying to do is unschedule (from the main thread) and reschedule (to a helper/network thread) an open NSInputStream and NSOutputStream that I am receiving from a third party framework (see Can an open, but inactive, NSStream that is scheduled on the main thread be moved to a different thread?). Nobody has answered that question thus far, so I am trying to do this myself to see if it could be made to work.
To test what is possible, I am trying to modify the code here (which includes a iOS client and a very short, python-based server [awesome!]):
http://www.raywenderlich.com/3932/how-to-create-a-socket-based-iphone-app-and-server
so that after the NSInputStream and NSOutputStream is created and opened I attempt to move it onto a helper thread.
The challenge that I am experiencing is that the helper thread does not seem to be responding to delegate messages from the streams or any messages that I am sending via:
performSelector:onThread:withObject:waitUntilDone:modes:. I suspect that I am doing something wrong with setting up the helper thread's NSRunLoop (see networkThreadMain below).
So, [ChatClientViewController viewDidLoad] now looks like:
- (void)viewDidLoad {
[super viewDidLoad];
[self initNetworkCommunication];
[self decoupleStreamsFromMainThread];
[self spoolUpNetworkThread];
inputNameField.text = #"cesare";
messages = [[NSMutableArray alloc] init];
self.tView.delegate = self;
self.tView.dataSource = self;
}
With these implementations:
- (void) initNetworkCommunication {
CFReadStreamRef readStream;
CFWriteStreamRef writeStream;
CFStreamCreatePairWithSocketToHost(NULL, (CFStringRef)#"localhost", 80, &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];
}
- (void) decoupleStreamsFromMainThread
{
inputStream.delegate = nil;
outputStream.delegate = nil;
[inputStream removeFromRunLoop: [NSRunLoop currentRunLoop] forMode: NSDefaultRunLoopMode];
[outputStream removeFromRunLoop: [NSRunLoop currentRunLoop] forMode: NSDefaultRunLoopMode];
}
- (void) spoolUpNetworkThread
{
[NSThread detachNewThreadSelector: #selector(networkThreadMain) toTarget: self withObject: nil];
}
- (void) networkThreadMain
{
NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; // Top-level pool
static dispatch_once_t once;
dispatch_once(&once, ^{
[self rescheduleThreads];
((ChatClientAppDelegate * )[[UIApplication sharedApplication] delegate]).networkThread = [NSThread currentThread];
[inputStream setDelegate:self];
[outputStream setDelegate:self];
NSLog(#"inputStream status is: %#", [NSInputStream streamStatusCodeDescription: [inputStream streamStatus]]);
NSLog(#"outputStream status is: %#", [NSOutputStream streamStatusCodeDescription: [outputStream streamStatus]]);
[[NSRunLoop currentRunLoop] runUntilDate: [NSDate distantFuture]];
});
[pool release]; // Release the objects in the pool.
}
- (void) rescheduleThreads
{
[inputStream scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
[outputStream scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
}
Any ideas on what might be wrong? Thanks in advance!

Answer 1

Something along the lines of the code in the question below works well ( I have similar code in my app):
How to properly open and close a NSStream on another thread