问题
I got confused about some issues:
1: The one month duration of auto-renewable subscriptions is 30 days or does it depend on a natural month?
Because I can only test in sandbox mode，so the duration is just several minutes... Maybe Apple just simply calculates it like this: 2013\01\15 -> 2013\02\15 -> 2013\03\15. If so,the second issue comes up
2: For example: I buy a monthly auto-renewable subscriptions at 2013\03\31 ,because 2013\04 only has 30 days, then what is the expires_date of my subscriptions? 2013\04\30 or 2013\05\01 or other date ?
回答1:
It's adding 1 month, not 30 days. The number of days in 1 month varies. So purchasing a subscription on 3/31 would end on 4/30.
You can use NSDate, NSCalendar, and NSDateComponents to add a month to a date and see how long it will last. More info here: Modifying NSDate to represent 1 month from today
来源：https://stackoverflow.com/questions/15411408/auto-renewable-subscriptions-how-long-a-month-is