Suppose we want to find the day of the week according to the given date i.e if we want to know the week day of a particular date then the following lines of code will help you to implement this :-

NSDate *date =  [NSDate date];  // get todays date

NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init] ;

[dateFormatter setDateFormat:@"EEEE"];   //set the dateFormat

NSLog(@"Week day of selected date -> %@", [dateFormatter stringFromDate:date]);

We can also get the number of day i.e if the day is TUESDAY then the output will be 3. The following code will implement it :-

NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSCalendarIdentifierGregorian];
 
NSDateComponents *comps = [gregorian components:NSCalendarUnitWeekday fromDate:[NSDate date]];

NSInteger weekday = [comps weekday];

NSLog(@"Number of day = %ld",(long)weekday);

The output for the above lines of code will be :-

Week day of selected date -> Tuesday
Number of day = 3