CODEWITHSUNDEEP
iosobjective-cnsdatetimespannsdatecomponents
Erik
Erik

Reputation: 2530

Split NSDate that stretches over several days into several spans

I have 2 NSDates that define a span, one could set them like this

spanA: 12:00 today
spanB: 12:00 tomorrow

This equals to 24 hours, but I need to create two ranges instead of one, so that no spans will stretch across midnight. The outcome of the example above would look like this:

spanA: 12:00 today
spanB: 23:59 today

spanC: 00:01 tomorrow
spanD: 12:00 tomorrow

I'm not sure how to do this. I came up with an idea to use a function like this:

- (NSInteger)daysBetweenDate:(NSDate *)fromDateTime andDate:(NSDate *)toDateTime
{
NSDate *fromDate;
NSDate *toDate;

NSCalendar *calendar = [NSCalendar currentCalendar];

[calendar rangeOfUnit:NSCalendarUnitDay startDate:&fromDate
             interval:NULL forDate:fromDateTime];
[calendar rangeOfUnit:NSCalendarUnitDay startDate:&toDate
             interval:NULL forDate:toDateTime];

NSDateComponents *difference = [calendar components:NSCalendarUnitDay
                                           fromDate:fromDate toDate:toDate options:0];

return [difference day];
}

which returns how many days the span stretches across, or in other words: the number of spans required. Then I could for instance for-loop the number of days and add some logic to create the necessary spans.

I'm using this as a structure for the spans:

typedef struct
{
NSTimeInterval start;
NSTimeInterval end;
} span;

What would be the best approach for this?

Upvotes: 2

Views: 107

Answers (1)

Sergey Kalinichenko
Sergey Kalinichenko

Reputation: 727137

Since all spans except possibly the first and last one are identical day-long spans, you can use this algorithm:

  • Check if the initial time is a midnight. If it is not a midnight, add an opening span from start to midnight of the same day
  • For each day after the first midnight add a day-long range to midnight of the next day
  • Check if the last time is a midnight. If it is not a midnight, add a closing span to the result.

Upvotes: 2

Related Questions