I want to make a UILocalNotification repeat every week, before iOS7 I would use localNotification.repeatInterval = NSWeekCalendarUnit - except
These don't appear to be documented but most likely NSCalendarUnitWeekOfYear will be a value from 1-53 (or maybe 0-52) representing the week number within the calendar year while NSCalendarUnitWeekOfMonth will be 1-5 (or maybe 0-4) representing the week within the month.
This all assumes Gregorian calendar. I can't speak to other calendar types.
It seems that NSCalendarUnitWeekOfMonth is equal to kCFCalendarUnitWeekOfMonth which is defined as "Specifies the original week of a month calendar unit." and NSCalendarUnitWeekOfYear is equal to kCFCalendarUnitWeekOfYear which is defined as "Specifies the original week of the year calendar unit.".