iphone - How to handle socket connection's events when app is in background?

Question

I want use the following function even when app is in background?

- (void)stream:(NSStream *)theStream handleEvent:(NSStreamEvent)streamEvent
 {
        case NSStreamEventHasBytesAvailable:
        {  NSLog(@"Event:NSStreamEventHasBytesAvailable");
            if (theStream == _inputStream) {

                NSLog(@"NSStreamEventHasBytesAvailable: on Input Stream");
                uint8_t buffer[1024];
                int len;

                while ([_inputStream hasBytesAvailable]) {
                    len = [_inputStream read:buffer maxLength:sizeof(buffer)];
                    if (len > 0) {

                        NSString *output = [[NSString alloc] initWithBytes:buffer length:len encoding:NSASCIIStringEncoding];

                        if (nil != output) {

                            NSLog(@"server said: %@", output);
                             // to get local notification I am calling below method.
 [self scheduleNotification];       
                        }
                    }
                }
            }
            break;
        }

The above code is working done in foreGround. I have made all the change given in apple document to the run the app in the background mode- voip. What should i write in AppDelegate method?

- (void)applicationDidEnterBackground:(UIApplication *)application
{
}

How to get the stream:handleEvent called in background?

Answer 1

I was dealing with similiar problem a while ago. Few important things to keep in mind:

• background "voip" functionality only works on device - don't use simulator to test it
• you will probably (tested) got rejected if your app registers as a voip app and isn't really voip app

So if this is not a voip app you might actually want to use remote notifications to alert user directly rather than showing local notification. I guess this is the only way for your app to pass App Store validation.

Anyway, two links here on SO helped you might find helpful:

How can an iOS app keep a TCP connection alive indefinitely while in the background?

I ended up using voip (as you do) and playing silent audio loop as suggested here - it worked. Not sure if this silent audio loop is still neccessary.

What happens to TCP and UDP (with multicast) connection when an iOS Application did enter background

Make sure you read Tips for Developing a VoIP App and Technical Note TN2277:Networking and Multitasking