Upvote:3

Aprove answer 
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    // Override point for customization after application launch.

    if ([[NSUserDefaults standardUserDefaults] objectForKey:@"LastLoginTime"] != nil)
    {
        NSDate *lastDate = [[NSUserDefaults standardUserDefaults] objectForKey:@"LastLoginTime"];
        NSDate *currentDate = [NSDate date];

        NSTimeInterval distanceBetweenDates = [currentDate timeIntervalSinceDate:lastDate];
        double secondsInAnHour = 3600;
        NSInteger hoursBetweenDates = distanceBetweenDates / secondsInAnHour;

        if (hoursBetweenDates >= 24)
        {
            //Perform operation here.
        }
    }

    [[NSUserDefaults standardUserDefaults] setObject:[NSDate date] forKey:@"LastLoginTime"];//Store current date

    return YES;
}

Upvote:5 

-(void)timeChange
{
  if ([[NSUserDefaults standardUserDefaults] objectForKey:@"LastLoginTime"] != nil)
  {
    NSDate *lastDate = [[NSUserDefaults standardUserDefaults] objectForKey:@"LastLoginTime"];
    NSDate *currentDate = [NSDate date];

    NSTimeInterval distanceBetweenDates = [currentDate timeIntervalSinceDate:lastDate];
    double secondsInAnHour = 3600;
    NSInteger hoursBetweenDates = distanceBetweenDates / secondsInAnHour;

    if (hoursBetweenDates >= 24)
    {
        //Perform operation here.
    }
  }

  [[NSUserDefaults standardUserDefaults] setObject:[NSDate date] forKey:@"LastLoginTime"];//Store current date
}

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