iOS VoIP application exit from backround after a while

Question

I set my .plist to run the application while background and I've set up the connection like this:

CFReadStreamRef     readStream;
CFWriteStreamRef    writeStream;

//open c socket:
int rc; // ret code of s.c. 
int my_socket;
struct sockaddr_in dest_addr;

my_socket = socket(AF_INET, SOCK_STREAM, 0); 
assert(my_socket >= 0);

dest_addr.sin_family = AF_INET; 
dest_addr.sin_port = htons(SERVER_LOC_PORT); 
dest_addr.sin_addr.s_addr = inet_addr(SERVER_IP); 

memset(dest_addr.sin_zero, 
       '\0',
       sizeof dest_addr.sin_zero);

rc = connect(my_socket,
             (struct sockaddr *)&dest_addr,
             (socklen_t) sizeof(dest_addr));

if(rc != 0){
    return NO ;
}

NSLog(@"Start connection");

// Open a stream based on the existing socket.  Then configure 
// the stream for async operation.

CFStreamCreatePairWithSocket(NULL, my_socket, &readStream, &writeStream);
assert(readStream != NULL);

self.networkStreamIn = (NSInputStream *) readStream;
self.networkStreamOut = (NSOutputStream *) writeStream;

//releasers
CFRelease(readStream);
CFRelease(writeStream);

self.networkStreamIn.delegate = self;
self.networkStreamOut.delegate = self;
BOOL res = [self.networkStreamIn setProperty:NSStreamNetworkServiceTypeVoIP 
                   forKey:NSStreamNetworkServiceType];

if(!res){
    NSLog(@"Cannot connect") ;
    // @TODO: Error handling here
}

[self.networkStreamIn scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];

[self.networkStreamIn open];
[self.networkStreamOut open];

Also I set my stream() to be called when data is received. Then I read an write from/in server. It's work. on backgrount too. but after few minutes (in backgound mode only!) the server print into the log "java.net.SocketTimeoutException: Read timed out". and no more connection with the client (iOS device).
I've not set background handler to retiain connection - but it should be work without this handler (I think..)!

Did I missed something with this socket configurations?

avishic avishic · Accepted Answer · 2012-05-10T12:14:25

VoIP app has restrictions at background. In short:

While app is at background, it is suspended most of the time
While it is suspended, the OS keeps your socket alive
App wakes up from suspention for: incoming data, network changes and performing KeepAlive to allow the server know its alive
While Audio is active (There is an active VoIP call), app may run fully at background.

Here is a link to a more detailed answer on another thread: VoIP app behavior at background

iOS VoIP application exit from backround after a while

1 Answers