I want to pass a `NSString` from one view controller to another when calling "popViewControllerAnimated". 

I have this in `ScheduleExerciseViewController`: 

```
    CalendarMainViewController *controller = [[CalendarMainViewController alloc]init];
    NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
    [formatter setDateFormat:@"yyyy-MM-dd"];
    NSString *fromDate = [formatter stringFromDate:self.dateCellsManager.startDate];
    NSLog(@"fromDate: %@", fromDate);
    [controller setPutDateHere:fromDate];

    //Pop the controller view controller
    [self.navigationController popToViewController:controller animated:YES];

```

In `CalendarMainViewController.h` I have:

```
@property (strong, nonatomic) NSMutableArray *datesWithEvent;
@property (nonatomic,retain) NSString *putDateHere;

```

And In `CalendarMainViewController` I have: 

```
-(void) viewWillAppear:(BOOL)animated{
    self.tabBarController.title = @"Calendar";
    NSLog(@"putDataHere: %@", _putDateHere);
    NSLog(@"datesWithEvents: %@", _datesWithEvent);
}

```

It prints "null" in both.

Any suggestions/comments/feedbacks?