gistfile1.txt

_source = dispatch_source_create(DISPATCH_SOURCE_TYPE_READ, mysocket, 0, dispatch_get_main_queue());
dispatch_source_set_event_handler(_source, ^{
  // do something with mysocket, because it has changed (has read, write or error)
};
dispatch_source_set_cancel_handler(source, ^{
  close(mysocket);
});
dispatch_resume(_source);

// sen för att stänga socket:
dispatch_source_cancel(_source);
dispatch_release(_source);