它是一种只在CloudKit中存储日期，没有时间的方法吗？

Question

I do not want to store time in CloudKit , any way to avoid it? The problem that I get date from UIDatePicker , and even dow I set only date ( dp.datePickerMode = .Date ) redundant time info will be stored in CloudKit too. Red marked number was not set via date picker.

Answer 1

NSDate has no concept of minutes, hours, seconds, day, months, years. NSDate is purely a reference to a single point in time.

It is only when you display a date into a readable format (like a string) that you see anything like Years, Months, Days, Hours, etc...

That is a product of the fact that an NSDate gets rendered into a human readable string for debugging.

If you don't want to show the date then don't show the date. The fact is though, someone's date of birth does actually contain hours, minutes and seconds it's just by convention that we decide to truncate it down to days only.

Just use the NSDate and when you display it just only display the date part.

BTW

When you don't show the time in a UIDatePicker then the current time will be used.

Answer 2

There are lots of reasons to only store a date. Apple does not provide one. So use an ISO - like format, 2014/06/22 in a string.

Storing a time and date when you only have a date, (like a birthday or calendar day) is usually not a good practice. One huge pitfall of storing an NSDate when you only want a day is that you will usually get the displayed date changing depending on what time zone you show it from. People's birthdays don't change based on timezone.