How do I find out which segue called the destination in an unwind segue?

Question

I have a unwind segue in my WishlistVC (a VC that lists all wishlists). Now, this VC allows a user to tap on a wishlist and, if it's empty, bring up the EditWishlistItems VC so one can select which items to put inside that wishlist. The WishlistVC also has another button that allows a user to create a new wishlist, and then invokes the EditWishlistItems so the user can add items to the new wishlist. Both these are different segues to the same VC.

When I unwind, I want to know who invoked the EditWishlistItems VC, i.e. which segue did I perform going forward in my unwind segue. If it's from the addItemsToWishlist modal segue, then I want to add the wishlist to Core Data, and if it's from editWishlistItems modal segue, I want to edit the wishlist's items in CD.

Any way to know this information when I unwind?

Answer 1

I would do it by adding a property

@property (nonatomic, strong) NSString *recentSegue;

and then creating

-(void)addItemsToWishList:{
     //business logic
     self.recentSegue = @"addItems";
    [self performSegueWithIdentifier:@"EditWishlistItems" sender:self];
}

-(void)editWishListItems:{
    //business logic
    self.recentSegue = @"editItems";
    [self performSegueWithIdentifier:@"EditWishlistItems" sender:self];
}

Then link your buttons to those methods rather than directly performing segues

and finally

-(void)viewDidAppear:(BOOL)animated {
    [super viewDidAppear:animated];
     if(self.recentSegue){
          if(self.recentSegue isEqualToString:@"addItems") { 
               //do Whatever
          } else if(self.recentSegue isEqualToString:@"editItems") { 
               //do whatever else
          }
          self.recentSegue = nil;
     }
}

While this should work, another way that might be better depending on your design is to let the EditWishListItems handle the coredata interaction directly.

Answer 2

THE_DOM's answer is good, but this is how I fixed my issue.

To see whether or not we need to modally segue, we check and see if our wishlist has no items in it in the following delegate method. If not, we tell it to segue. If it does have items, the push segue will automatically get called instead (set up in IB).

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    Wishlist *wishlist = [self.fetchedResultsController objectAtIndexPath:indexPath];
    if([wishlist.items count] == 0) {
        // execute our segue
        [self performSegueWithIdentifier:@"editWishlistItems" sender:self];
    }
}

In our prepareForSegue, we set a BOOL to indicate the user tapped on an empty wishlist (this is in our destination VC).

-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
    NSIndexPath *indexPath = [self.tableView indexPathForSelectedRow];
    ... // other segues
    if([segue.identifier isEqualToString:@"editWishlistItems"])
    {
        UINavigationController *navigationVC = (UINavigationController *)segue.destinationViewController;
        ManageWishlistItemCDTVC *manageWishlistItemVC = (ManageWishlistItemCDTVC *)navigationVC.topViewController;
        manageWishlistItemVC.tappedOnEmptyWishlist = YES;
        manageWishlistItemVC.wishlist = [self.fetchedResultsController objectAtIndexPath:indexPath];
    }
}

And then, when we unwind, we check to see if the BOOL is YES or NO.

- (IBAction)saveWishlistItem:(UIStoryboardSegue *)segue {
    ManageWishlistItemCDTVC *manageWishlistItemVC = (ManageWishlistItemCDTVC *)segue.sourceViewController;

    // check to see if we came from edit segue or add segue
    if(manageWishlistItemVC.tappedOnEmptyWishlist) { // edit segue
        // saved edited wishlist
    } else { // add segue
        if([manageWishlistItemVC.selectedItems count] > 0) {
            // save new wishlist
    }
}