Objective-C LanguageNSCalendar

System Locale Information

+currentCalendar returns the logical calendar for the current user.

    NSCalendar *calender = [NSCalendar currentCalendar];
    NSLog(@"%@",calender);

+autoupdatingCurrentCalendar returns the current logical calendar for the current user.

NSCalendar *calender = [NSCalendar autoupdatingCurrentCalendar];
NSLog(@"%@",calender); 

Initializing a Calendar

- initWithCalendarIdentifier: Initializes a newly-allocated NSCalendar object for the calendar specified by a given identifier.

NSCalendar *calender = [[NSCalendar alloc]initWithCalendarIdentifier:@"gregorian"];
NSLog(@"%@",calender);

- setFirstWeekday: Sets the index of the first weekday for the receiver.

NSCalendar *calender = [NSCalendar autoupdatingCurrentCalendar];
[calender setFirstWeekday:1];
NSLog(@"%d",[calender firstWeekday]);

- setLocale: Sets the locale for the receiver.

NSCalendar *calender = [NSCalendar autoupdatingCurrentCalendar];
[calender setLocale:[NSLocale currentLocale]];
NSLog(@"%@",[calender locale]);

- setMinimumDaysInFirstWeek: Sets the minimum number of days in the first week of the receiver.

NSCalendar *calender = [NSCalendar autoupdatingCurrentCalendar];
[calender setMinimumDaysInFirstWeek:7];
NSLog(@"%d",[calender minimumDaysInFirstWeek]);     

- setTimeZone: Sets the time zone for the receiver.

NSCalendar *calender = [NSCalendar autoupdatingCurrentCalendar];
[calender setTimeZone:[NSTimeZone timeZoneForSecondsFromGMT:0]];
NSLog(@"%@",[calender timeZone]);

Calendrical Calculations

- components:fromDate: Returns a NSDateComponents object containing a given date decomposed into specified components

NSCalendar *calender = [NSCalendar autoupdatingCurrentCalendar];
[calender setTimeZone:[NSTimeZone timeZoneForSecondsFromGMT:0]];
NSLog(@"%@",[calender components:NSCalendarUnitDay fromDate:[NSDate date]]);
NSLog(@"%@",[calender components:NSCalendarUnitYear fromDate:[NSDate date]]);
NSLog(@"%@",[calender components:NSCalendarUnitMonth fromDate:[NSDate date]]);

- components:fromDate:toDate:options: Returns, as an NSDateComponents object using specified components, the difference between two supplied dates.

 NSCalendar *calender = [NSCalendar autoupdatingCurrentCalendar];
[calender setTimeZone:[NSTimeZone timeZoneForSecondsFromGMT:0]];
NSLog(@"%@",[calender components:NSCalendarUnitYear fromDate:[NSDate dateWithTimeIntervalSince1970:0] toDate:[NSDate dateWithTimeIntervalSinceNow:18000] options:NSCalendarWrapComponents]);

- dateByAddingComponents:toDate:options: Returns a new NSDate object representing the absolute time calculated by adding given components to a given date.

NSCalendar *calender = [NSCalendar autoupdatingCurrentCalendar];
NSDateComponents *dateComponent = [[NSDateComponents alloc]init];
[dateComponent setYear:10];
NSLog(@"%@",[calender dateByAddingComponents:dateComponent toDate:[NSDate             dateWithTimeIntervalSinceNow:0] options:NSCalendarWrapComponents] );

- dateFromComponents: Returns a new NSDate object representing the absolute time calculated from given components.

NSCalendar *calender = [NSCalendar autoupdatingCurrentCalendar];
NSDateComponents *dateComponent = [[NSDateComponents alloc]init];
[dateComponent setYear:2020];
NSLog(@"%@",[calender dateFromComponents:dateComponent]);