Why NSCalendar's dateFromComponents returns wrong date?

问题

I am expecting 2010-10-11 00:00:00

But instead I receive 2010-10-10 21:00:00 +0000

I know, that I can add a few hours and receive desired date, but I do not understand why I get previous day with 21 hours...

Please, help!

NSDateComponents *comps = [[NSDateComponents alloc] init];
[comps setYear:2010];
[comps setMonth:10];
[comps setDay:11];

[comps setHour:0];
[comps setMinute:0];
[comps setSecond:0];

NSCalendar *cal = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSDate *retDate = [cal dateFromComponents:comps];

回答1:

I think your problem may be solved by setting the NSTimeZone.

回答2:

If you need a specific time format use that formatter or else write this to get correct time. first option...

let formatter = NSDateFormatter()
    formatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSSZ"
    let localDate = formatter.dateFromString("1989-10-17T05:00:00.000-0000")

or if you need date from components use the below code like ...

let calendar = NSCalendar.currentCalendar()
    calendar.timeZone = NSTimeZone(name: "GMT")!
    let date = calendar.dateFromComponents(components)

or you need

来源：https://stackoverflow.com/questions/4322687/why-nscalendars-datefromcomponents-returns-wrong-date