How to populate an array from detailViewController and return to masterViewController in iOS?

Question

I have a tableView from which I navigate to a 'viewController' ie PassengerInfoViewController in which I have a form.I fill up the form , make a dictionary out of it and add it to a NSMutableArray.

So when I am going back to the tableView' I would like to pass this array and then reload thetableView` with the filled array.

So here's what I am doing : -

  //navigate to the form
  - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{

  PassengerInfoViewController *pivc = [self.storyboard instantiateViewControllerWithIdentifier:@"PassengerInfoViewController"];
  [self.navigationController pushViewController:pivc animated:YES];

}

 //After filling up the form 

 -(void)goBackToPassengerDetails:(UIButton*)sender{

   NSString *title = self.titleTextField.text;
   NSString *fname = self.firstNameTextField.text;
   NSString *lname =self.lastNameTextField.text;
   NSString *ageStr = self.ageTextField.text;

   NSMutableDictionary *dict = [[NSMutableDictionary alloc]init];
   [dict setValue:title forKey:@"title"];
   [dict setValue:fname forKey:@"firstName"];
   [dict setValue:lname forKey:@"lastName"];
   [dict setValue:ageStr forKey:@"age"];
   Passenger *passengerObj = [Passenger sharedInstance]; //Singleton

   [passengerObj.passengerDetailArray addObject:dict];

    PassengerDetailsViewController *pdc = [self.storyboard instantiateViewControllerWithIdentifier:@"PassengerDetailsViewController"];
[pdc getPassengerinfo:passengerObj.passengerDetailArray];
[self.navigationController popViewControllerAnimated:YES];

Once I navigate back I reload the table view.However celForRow method doesn't populate new values.

 -(void)getPassengerinfo:(NSMutableArray*)arr{
  passenger_infoArray =[[NSMutableArray alloc]init];
  passenger_infoArray = arr;
  NSLog(@"Passenger Info Array : %@", passenger_infoArray);//Shows array of dictionaries

  [passengerInfoTableView reloadData];
}

My cellForRow method looks like this:

   - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
   //Not called when I am doing reload data
   static NSString *CellIdentifier = @"Cell";
   cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
   if (cell == nil)
   {
       cell = [[UITableViewCell alloc]initWithStyle:UITableViewCellStyleValue1 reuseIdentifier:CellIdentifier ];

   }
   NSLog(@"Table view array  : %@",passenger_infoArray); 
   if (passenger_infoArray.count>0) {

    NSString *temp= [[passenger_infoArray objectAtIndex:indexPath.row]objectForKey:@"firstName"];
    cell.textLabel.text = temp;
   }else{

    cell.textLabel.text = [NSString stringWithFormat:@"Passenger %ld", (long)indexPath.row+1];
    cell.imageView.image = [UIImage imageNamed:@"user.png"];

   }
     return cell;

  }

Answer 1

You can pass data to previous view controller by using delegate method

In PassengerInfoViewController.h add below code just above of your import statement

@protocol passengerInfoViewControllerdelegate <NSObject>
     -(void)sendData:(NSMutableArray *)arrData; 
@end

After this create one property, as shown below

@property(nonatomic,assign)id delegate;

Now, in PassengerInfoViewController.m synthesize the property and after that

-(void)viewWillDisappear:(BOOL)animated
{
    [delegate sendData:yourArray];
}

Now in tableview

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    PassengerInfoViewController *pivc = [self.storyboard instantiateViewControllerWithIdentifier:@"PassengerInfoViewController"];

    pivc.delegate = self;  //Add this line to your code

   [self.navigationController pushViewController:pivc animated:YES];
}

Now, it's time to implement delegate method which we created in viewcontroller

-(void)sendData:(NSMutableArray *)arrData
{
      passenger_infoArray = arrData;
     [passengerInfoTableView reloadData];
}

Answer 2

You can pass data using

1. Delegates
2. Notifications
3. Properties
4. Global variables

Using Delegates is good practice, and last two are not preferred.

Answer 3

Old way to do this was using delegates. Better way to do this is via an unwind segue because there's much less code and you don't have to create a protocol.

Once your form completes, your PDC should call [self performSegue:@"theNameOfTheUnwindSegueeYouCreateInTheStoryboard"]. Then, in your PDC's prepareForSegue method, get the destinationViewController property from the storyboardSegue parameter - this is your VC containing the Table View. Set whatever model property you're using to back the table view - in your case it looks to be the passenger_infoArray object, which you'll have to make mutable if isn't already and also expose publicly if it isn't already.