How do I calculate the number of days in this year in Objective C

Question

How can i calculate the number of days in a year for any calendar, not just gregorian. I have tried this

NSUInteger *days = [[NSCalendar currentCalendar] range

Answer 1

Another example in Swift 3:

let calendar = Calendar.current
let date = Date() // use any date in this year
if let yearInterval = calendar.dateInterval(of: Calendar.Component.year, for: date),
   let daysInYear = calendar.dateComponents([Calendar.Component.day], from: yearInterval.start, to: yearInterval.end).day
{
    print(daysInYear)
}

In Objective-C:

NSCalendar *calendar = [NSCalendar currentCalendar];
NSDate* date = [NSDate date];
NSDate* startOfYear = nil;
NSTimeInterval yearDuration = 0;
if ([calendar rangeOfUnit:NSCalendarUnitYear startDate:&startOfYear interval:&yearDuration forDate:d
]) {
    NSDateComponents *daysComponents = [calendar components:NSCalendarUnitDay fromDate:startOfYear toDate:[startOfYear dateByAddingTimeInterval:yearDuration] options:0];
    NSInteger daysInYear = daysComponents.day;
    NSLog(@"Days in year: %ld", daysInYear);
}

Answer 2

Swift 3 extension:

extension Date {
    public func isLeapYear() -> Bool {
        let components = Calendar.current.dateComponents([.year], from: self)

        guard let year = components.year else { return false }

        return (year % 4 == 0 && year % 100 != 0) || (year % 400 == 0)
    }
}

Answer 3

Maybe you can use the components:fromDate:toDate:options: selector which is meant to (and I quote official Apple docs): Returns, as an NSDateComponents object using specified components, the difference between two supplied dates. ?

Also read this post that clarifies the behaviour you are seeing.

Answer 4

Wow, those are involved solutions. Just create a date of February 29 of the current year and see if it's converted to march first or not.

-(BOOL)isLeapYear {
    NSDateComponents *components = [[NSDate currentCalendar] components:componentFlags fromDate:self];
    components.month = 2;
    components.day = 29;

    NSDate *date = [[NSDate currentCalendar] dateFromComponents:components];
    return (date.month == 2 && date.day == 29);
}

** Note, some of these items like date.month and date.day relay on other methods not shown, but you'll get the idea.

Answer 5

Here is the answer provided by William Clemens but in Objective C:

                    int year;
                    int yearCode;

                    if ( year % 400 == 0 )
                        {yearCode = 366;} // Leap Year
                    else if ( year % 100 == 0 )
                    {
                        {yearCode = 365;} // Non Leap Year
                    }
                    else if ( year % 4 == 0 )
                    {
                         {yearCode = 366;} // Leap Year
                    }
                    else
                    {yearCode = 365;} // Non-Leap Year

Answer 6

I don't know if anybody is still interested in this thread, but is another possible solution:

NSCalendar *calendar = [NSCalendar currentCalendar];
NSDate *startOfYear;
NSTimeInterval lengthOfYear;
[calendar rangeOfUnit:NSYearCalendarUnit
            startDate:&startOfYear
             interval:&lengthOfYear
              forDate:[NSDate date]];
NSDate *endOfYear = [startOfYear dateByAddingTimeInterval:lengthOfYear];
NSDateComponents *comp = [calendar components:NSDayCalendarUnit
                                     fromDate:startOfYear
                                       toDate:endOfYear
                                      options:0];
NSUInteger numberOfDaysInThisYear = [comp day];

using only 2 calls to NSCalendar.