ios - How to find people using my app within a wifi network

Question

Hi I want to find all people using my app within a same network, say if its a wifi network then i want to get all people using my app in that particular network.

their profile data existing in my database (mySQL) with their location. I can get the users As per location But my Question is to find them as per network. Any ideas how to start to do that?

Answer 1

Im not saying using Bonjour (Zeroconf) is the best way to achieve what you want - but you can certainly achieve your goal using it.

Bonjour is used in two ways: - publishing a service - detecting (browsing for) available services

For your task you'd have to do both.

One basic description can be found here: Bonjour Overview and its application in iOS

If you decide to use Bonjour then you'll find a lot of documentation on Bonjour for Developers

Basically, you need to publish a service: Bonjour Programming > Section 18.2. Publishing a Service

The publishing class (usually appDelegate ) should be also a NSNetService delegate.

NSNetService *netService; //an ivar or a property

//creating and publishing a service
netService = [[NSNetService alloc] initWithDomain:@""
                                             type:@"_yourservicename._tcp."
                                             name:@""
                                             port:9876];
//if your app actually acts as a server port: should be it's port,
//otherwise it could be any free port

netService.delegate = self;
[netService publish];

You should also handle delegate methods (and some appDelegate methods):

-(void)netService:(NSNetService *)aNetService
    didNotPublish:(NSDictionary *)dict
{
    NSLog(@"Service did not publish: %@", dict);
}

- (void)applicationWillTerminate:(UIApplication *)application {
    //---stop the service when the application is terminated---
    [netService stop];
}

- (void)applicationDidEnterBackground:(UIApplication *)application {
    //---stop the service when the application is paused---
    [netService stop];
}

- (void)applicationWillEnterForeground:(UIApplication *)application
{
    [netService publish];
}

And browse for existing services: Bonjour! (cocoanetics) (you'll only need the bottom part of the page)

serviceBrowser = [[NSNetServiceBrowser alloc] init];
serviceBrowser.delegate = self;
[serviceBrowser searchForServicesOfType:@"_yourservicename._tcp." inDomain:@""];

- (void)netServiceBrowser:(NSNetServiceBrowser *)aNetServiceBrowser 
    didFindService:(NSNetService *)aNetService moreComing:(BOOL)moreComing
{
    [self willChangeValueForKey:@"foundServices"];
    [_foundServices addObject:aNetService];
    [self didChangeValueForKey:@"foundServices"];
 
    NSLog(@"found: %@", aNetService);
}
 
- (void)netServiceBrowser:(NSNetServiceBrowser *)aNetServiceBrowser 
    didRemoveService:(NSNetService *)aNetService moreComing:(BOOL)moreComing
{
    [self willChangeValueForKey:@"foundServices"];
    [_foundServices removeObject:aNetService];
    [self didChangeValueForKey:@"foundServices"];
 
    NSLog(@"removed: %@", aNetService);
}

PS: Bonjour might be tricky to start with but it is certainly a useful knowledge.

Depends on what user experience exactly you want. A good alternative to Bonjour would most certainly be GameKit ( GKPeerPickerController ) where user can actually select to which devices (peers he wants to connect to). This should work in Wi-Fi or via BlueTooth.

Answer 2

One way of doing service discovery is to have your program listen on a port and then doing a broadcast on that port when you want to be discovered or poll for other entities. Something along these lines.

 socket = listen_and_stuff()
 others = do_broadcast()
 while(run)
     if time to update
         others = do_broadcast
     if received request
         reply with info about self

But, broadcast depends a bit on router settings, subnetworks and so on so it might not work in all cases.