Calculating the Difference Between Two Time Periods in Objective-C

Objective-C is a superset of C that adds object-oriented capabilities and dynamic runtime features. It’s commonly used for macOS and iOS development.

When dealing with time in Objective-C, the Foundation framework provides powerful tools like NSDate, NSDateComponents, and NSCalendar for accurate calculations.

In this sub-article, we’ll write an Objective-C program that calculates the difference between two time values using NSDate and NSDateComponents.

This approach mirrors the logic of our lead C article, but is adapted to the object-oriented nature of Objective-C.

Objective-C Program: Calculate the Difference Between Two Time Periods

// DIFFERENCE BETWEEN TWO TIME PERIODS in Objective-C using NSDate and NSCalendar

#import <Foundation/Foundation.h>

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        // Step-1 Define date formatter and input time strings
        NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
        [formatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"];

        NSDate *startTime = [formatter dateFromString:@"2025-11-15 08:20:00"];
        NSDate *endTime   = [formatter dateFromString:@"2025-11-22 15:05:45"];

        // Step-2 Use NSCalendar to calculate the difference
        NSCalendar *calendar = [NSCalendar currentCalendar];
        NSDateComponents *components = [calendar components:(NSCalendarUnitHour | NSCalendarUnitMinute | NSCalendarUnitSecond)
                                                   fromDate:startTime
                                                     toDate:endTime
                                                    options:0];

        // Step-3 Display the result
        NSLog(@"\nTIME DIFFERENCE: %ld HOURS, %ld MINUTES, %ld SECONDS",
              (long)[components hour],
              (long)[components minute],
              (long)[components second]);
    }
    return 0;
}

Output

Explanation

• NSDateFormatter is used to parse string-based date-time into NSDate objects.

• NSCalendar and NSDateComponents help calculate time difference precisely.

• The result is broken down into hours, minutes, and seconds for clarity.

This approach is commonly used in iOS apps that track event durations, manage calendar events, or compute intervals between user actions.

Extra Metric: Time Difference in Total Minutes

You can also calculate the total difference in minutes:

NSTimeInterval timeInterval = [endTime timeIntervalSinceDate:startTime];

NSInteger totalMinutes = timeInterval / 60;

NSLog(@"TOTAL MINUTES: %ld", (long)totalMinutes);

Output

This metric is helpful when storing or transmitting time data compactly.