举例说明，a与b无关注关系，a广播状态给b，b可以收到。然后a与b建立关注关系，a广播给b，还是可以收到。一旦a与b取消关注关系，a再广播状态给b，b收不到。不过若a与b再次建立关注后，b又可以收到了。
代码：
广播
let status = AVStatus()
status.data = post.data
let query = AVUser.query()
query.whereKey("objectId", containedIn: allConnectionIDList)
status.setQuery(query)
status.sendInBackgroundWithBlock() { succeeded, error in
if !succeeded {
print("Error in sending: (error)")
}
}
接收广播
let query = AVStatus.inboxQuery(kAVStatusTypeTimeline)
query.includeKey("source")
query.findObjectsInBackgroundWithBlock() { objects, error in
if error == nil && objects.count != 0 {
let results = objects as! [AVStatus]
for result in results {
let post = Post(status: result, currentUser: AVUser.currentUser())
self.posts.append(post)
}
dispatch_async(dispatch_get_main_queue()) {
self.tableView.reloadData()
}
}