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How can I check to see if a date is inherently TOMORROW?

I don't want to add hours or anything to a date like today, because if today is already 22:59, adding too much would go over to the day after, and adding too little if the time is 12:00 would miss tomorrow.

How can I check two NSDates and ensure that one is the equivalent of tomorrow for the other?

waylonion
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    possible duplicate of [How can i get next date using NSDate?](http://stackoverflow.com/questions/1081689/how-can-i-get-next-date-using-nsdate) – raina77ow Oct 01 '12 at 22:31

3 Answers3

52

Using NSDateComponents you can extract day/month/year components from the date representing today, ignoring the hour/minutes/seconds components, add one day, and rebuild a date corresponding to tomorrow.

So imagine you want to add exactly one day to the current date (including keeping hours/minutes/seconds information the same as the "now" date), you could add a timeInterval of 24*60*60 seconds to "now" using dateWithTimeIntervalSinceNow, but it is better (and DST-proof etc) to do it this way using NSDateComponents:

NSDateComponents* deltaComps = [[[NSDateComponents alloc] init] autorelease];
[deltaComps setDay:1];
NSDate* tomorrow = [[NSCalendar currentCalendar] dateByAddingComponents:deltaComps toDate:[NSDate date] options:0];

But if you want to generate the date corresponding to tomorrow at midnight, you could instead just retrieve the month/day/year components of the date representing now, without hours/min/secs part, and add 1 day, then rebuild a date:

// Decompose the date corresponding to "now" into Year+Month+Day components
NSUInteger units = NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay;
NSDateComponents *comps = [[NSCalendar currentCalendar] components:units fromDate:[NSDate date]];
// Add one day
comps.day = comps.day + 1; // no worries: even if it is the end of the month it will wrap to the next month, see doc
// Recompose a new date, without any time information (so this will be at midnight)
NSDate *tomorrowMidnight = [[NSCalendar currentCalendar] dateFromComponents:comps];

P.S.: You can read really useful advice and stuff about date concepts in the Date and Time Programming Guide, especially here about date components.

electronix384128
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AliSoftware
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  • How do you work around the fact that `NSCalendar`'s `dateFromComponents` returns `nullable` result? I know that tomorrow always exists and want to use this fact while coding. However, when I use this approach in Swift `tomorrowMidnight` _may_ be `nil`, at least that's what the compiler thinks. – i4niac Nov 23 '15 at 07:12
7

In iOS 8 there is a convenience method on NSCalendar called isDateInTomorrow.

Objective-C

NSDate *date;
BOOL isTomorrow = [[NSCalendar currentCalendar] isDateInTomorrow:date];

Swift 3

let date: Date
let isTomorrow = Calendar.current.isDateInTomorrow(date)

Swift 2

let date: NSDate
let isTomorrow = NSCalendar.currentCalendar().isDateInTomorrow(date)
Kevin
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1

You might be able to leverage NSCalendar/Calendar to create tomorrow:

extension Calendar {
    var tomorrow: Date? {
        return date(byAdding: .day, value: 1, to: startOfDay(for: Date()))
    }
}
John Liedtke
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