比如想它每星期一，星期四，星期五通知用户
就这种不固定的重复提醒 该怎么弄？
NSLocalNotification有个属性，repeatInterval：
repeatInterval
The calendar interval at which to reschedule the notification.
@property(nonatomic) NSCalendarUnit repeatInterval
Discussion
If you assign an calendar unit such as weekly (NSWeekCalendarUnit) or yearly (NSYearCalendarUnit), the system reschedules the notification for delivery at the specified interval. The default value is 0, which means don't repeat.