该特性将取代 Calendar 中的通知，用于未被接受的邀请、重新排定的事件和委托通知。
This feature replaces notices in the Calendar for unaccepted invitations, rescheduled events, and delegation notices.
消息通知事件的委托方法，委托对象将要处理或已经处理。
The message informs the delegate of an event that the delegating object is about to handle or has just handled.
本例中，当数据从nsurlconnection中返回，它调用委托对象并通知它数据已准备好被解析并可以显示给用户。
In this case, when the data is returned from the NSURLConnection it calls the delegate object and informs it that the data is ready to be parsed so that it can be displayed to the user.
应用推荐