Number of days between two NSDate objects - ios

Question

I'm trying to compare two days of NSDate objects, I used at the first time NSDateComponents to calculate difference between my two dates Objects, but it is working correctly.
NSString *dateStr =#"2012-11-05 15:00:00";
NSDate *date = [dateFormat dateFromString:dateStr];
NSDateComponents *datesDiff = [calendar components: NSDayCalendarUnit
fromDate: date
toDate: [NSDate date]
options: 0];
That does not resolve my problem. Indeed when date1 = 2012-11-05 23:00:00 and date2 = 2012-11-06 10:00:00, the difference between the tow dates is 0 day and 11 hours.
I am looking for something that allows me to detect day changes, in other words when date1 = 2012-11-05 23:00:00 and date2 = 2012-11-06 00:01:00, there's one day diffrence.
If someone knows the solution for that, i would welcome his suggestion.
Thanks in advance

Answer 1

I think you are looking for this (from the Date and Time Programming Guide):
Listing 13 Days between two dates, as the number of midnights between
#implementation NSCalendar (MySpecialCalculations)
-(NSInteger)daysWithinEraFromDate:(NSDate *) startDate toDate:(NSDate *) endDate
{
NSInteger startDay=[self ordinalityOfUnit:NSDayCalendarUnit
inUnit: NSEraCalendarUnit forDate:startDate];
NSInteger endDay=[self ordinalityOfUnit:NSDayCalendarUnit
inUnit: NSEraCalendarUnit forDate:endDate];
return endDay-startDay;
}
#end
EDIT: Swift version:
extension NSCalendar {
func daysWithinEraFromDate(startDate: NSDate, endDate: NSDate) -> Int {
let startDay = self.ordinalityOfUnit(.Day, inUnit: NSCalendarUnit.Era, forDate: startDate)
let endDay = self.ordinalityOfUnit(.Day, inUnit: NSCalendarUnit.Era, forDate: endDate)
return endDay - startDay
}
}

Answer 2

NSString *start = #"2010-09-01";
NSString *end = #"2010-12-01";
NSDateFormatter *f = [[NSDateFormatter alloc] init];
[f setDateFormat:#"yyyy-MM-dd"];
NSDate *startDate = [f dateFromString:start];
NSDate *endDate = [f dateFromString:end];
[f release];
NSCalendar *gregorianCalendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents *components = [gregorianCalendar components:NSDayCalendarUnit
fromDate:startDate
toDate:endDate
options:0];
[gregorianCalendar release];
components now holds the difference.
NSLog(#"%ld", [components day]);

Answer 3

func daysBetweenDates(startDate: NSDate, endDate: NSDate) -> Int
{
let calendar = NSCalendar.currentCalendar()
let components = calendar.components([.Day], fromDate: startDate, toDate: endDate, options: [])
return components.day
}
or
let calendar = NSCalendar.currentCalendar();
let component1 = calendar.component(.Day, fromDate: fromDate)
let component2 = calendar.component(.Day, fromDate: toDate)
let difference = component1 - component2

Answer 4

For Swift 3:
Expanding from #masa's answer:
extension Calendar {
func daysWithinEraFromDate(startDate: Date, endDate: Date) -> Int? {
guard let startDay = ordinality(of: .day, in: .era, for: startDate) else {
return nil
}
guard let endDay = ordinality(of: .day, in: .era, for: endDate) else {
return nil
}
return endDay - startDay
}
}