Difference between dateWithTimeInterval:(NSTimeinterval) sincedate:(nsdate *) and (nsdate *) dateByAddingTimeInterval:(NSTimeInterval)

Question

what is the difference between the two statements

NSDate *today = [NSDate date];
NSDate *tomarow = [today dateByAddingTimeInterval:60*60*24];
NSDate *nextday = [NSDate dateWithTimeInterval:60*60*24 sinceDate:today];

Answer 1

The only difference between the two methods is that one is a class method and the other is an instance method.

Following code snippet demonstrates the use of both methods:

// Today's Date
NSDate *today = [NSDate new];

// Date With Class Method
NSDate *tomorrow1 = [NSDate dateWithTimeInterval:60*60*24 sinceDate:today];
NSLog(@"Date from class method: %@", tomorrow1);

// Date With Instance Method
NSDate *tomorrow2 = [today dateByAddingTimeInterval:60*60*24];
NSLog(@"Date from instance method: %@", tomorrow2);

The above code snippet will give the output like following:

Date from class method: 2012-12-27 09:35:15 +0000

Date from instance method: 2012-12-27 09:35:15 +0000

for more information , see NSDate