How do I calculate date count difference between my app installed and device date from objective C

Question

How do I calculate date count difference between two days in objectice C formate.

Try this answer posted to a similar question: http://stackoverflow.com/a/4739550/1262527 — Mariam K., Apr 23 '13 at 14:37

score 2 · Answer 1 · answered Apr 23 '13 at 15:56

Check if Installation Date is Registered or not, if registered the Calculate date otherwise register it.

if([[NSUserDefaults standardUserDefaults] objectForKey:@"IDate"])
{
    NSDate *iDate = [[NSUserDefaults standardUserDefaults] objectForKey:@"IDate"];
    NSTimeInterval interval = [[NSDate date] timeIntervalSinceDate:iDate];
    int diff=interval/86400;//for converting seconds into days.
    NSLog(@"%d Days",diff);
}
else
{
    [[NSUserDefaults standardUserDefaults] setObject:[NSDate date] forKey:@"IDate"];
    [[NSUserDefaults standardUserDefaults] synchronize];
}

score 1 · Answer 2 · answered Apr 23 '13 at 14:55

if you mean something like a "trial time" and after that you have to register: I would do as followed:

    NSDate *installDate = [[NSUserDefaults standardUserDefaults] objectForKey:@"InstallationDate"];
    if(installDate)
    {
        // time in Seconds
        long int timePassed = [installDate timeIntervalSinceNow] * -1;
        NSLog(@"%ld", timePassed);

        // now do your calculations and compare
    }
    else // first start
    {
        [[NSUserDefaults standardUserDefaults] setObject:[NSDate date] forKey:@"InstallationDate"];
        [[NSUserDefaults standardUserDefaults] synchronize];

        NSLog(@"%@", [[NSUserDefaults standardUserDefaults] objectForKey:@"InstallationDate"]);
    }

(as addition to Danny's post)

score 0 · Answer 3 · edited Apr 23 '13 at 14:44

0

Store your device installed date in NSUserDefaults once its first run and then calculate that with the current date.

NSTimeInterval diff = [date2 timeIntervalSinceDate:date1]; // in seconds

edited Apr 23 '13 at 14:44

Andriy

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answered Apr 23 '13 at 14:33

Danny

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Note that this doesn't take into account time changes, leap years, etc. You should not calculate "days" between two dates this way. – lnafziger Apr 23 '13 at 15:28

How do I calculate date count difference between my app installed and device date from objective C

3 Answers3