Bonjour Quickie in Objective-C - Service Announcement and discovery in just 6 lines of code.

bonjour.m

// This is how you announce a service - saying i offer service _someservice._tcp. on port 4711

NSNetService *nets = [[NSNetService alloc] initWithDomain:@"local." type:@"_someservice._tcp." name:@"" port:4711];
[nets setDelegate:self];
[nets publish];

// And this is how you find a service

NSNetServiceBrowser *browser = [[NSNetServiceBrowser alloc] init];
[browser setDelegate:self];
[browser searchForServicesOfType:@"_someservice._tcp." inDomain:@"local."];	

// Isnt it great?