Like many date related operations, this isn’t as straightforward for a computer as it is for a human brain. Besides, it needs to be time-travel save as well as future proof. Here’s how we do it:
First we create a Gregorian calendar object and extract the current year from it. Next we’ll add the date components to it that make up New Year’s Eve, which will give us a second date object.
Now that we have two dates, we compare them via the NSCalendar method fromDate:toDate. This in turn will result in a new date component from which we can extract the days.
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// what year is this? who's the president? NSDate *today = [NSDate date]; NSCalendar *gregorian = [[NSCalendar alloc]initWithCalendarIdentifier:NSGregorianCalendar]; NSDateComponents *components = [gregorian components:NSYearCalendarUnit fromDate:today]; NSInteger currentYear = [components year]; NSLog(@"The year is %i", currentYear); // create a date with the end of the year [components setDay:31]; [components setMonth:12]; NSDate *newYearsEve = [gregorian dateFromComponents:components]; // determine how many days are left until the end of the year NSDateComponents *daysLeftComponents = [gregorian components:NSDayCalendarUnit fromDate:today toDate:newYearsEve options:0]; NSInteger daysLeft = [daysLeftComponents day]; NSLog(@"Days to New Years Eve: %ld", (long)daysLeft); |