Question

Sort of a simple question. I have a tableview in a navigationcontroller. When I touch a cell, it pushes a view controller with the information from the cell, so I can edit it in the new view. Now thats working correct (we can call it the informationpath: “rootviewcontroller -> pushed viewcontroller”). But when I click save in the new view, I want the edited values to travel back to the rootviewcontroller before I call popviewcontroller (informationpath: “pushed viewcontroller -> rootviewcontroller”), so the edited values can be displayed in the tableview.

Whats the correct approach to this?

EDIT:

pushViewController and popViewController is working. I only asked for the best approach to get the edited information back to the rootViewController for display in the tableview, when Save-button (popViewController) was called. I guess I’ll just have to edit the pList with the new information directly from the pushed viewController. Though I would prefer sending the new information to the rootViewController and have it handle the access to the pList-file.

Answer 1

I have the same situation – two tableviews. The first TV displays a list of database records and when one is tapped it goes through to the second TableView which displays the details of the record. I do this by pushing the details TableViewController onto the navigation controllers stack. So far so go and quite simple.

The problem I encountered was that after updating the record in the details table view (controller), I wanted to let the list table view controller know, so that it could update the list of records.

The first thing I did was to add a property to the details table view controller so that when a row was selected on the list of records, the list controller could pass the core data managed entity to the details controller.

At the same time, I also added the list controller as a observer of core data change events like this:

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(dataSaved:) name:NSManagedObjectContextDidSaveNotification object:nil];

So if the details table view and controller update the record, the list controller has it’s dataSaved: method called, passing a NSNotification object.

In the dataSaved: method I examine the object and if the core data entity being edited is in the updated list, then I set a flag to signal an update is required. However if there is a record in the inserted list, it means that a new record has been created and inserted into the database, so a flag is set to trigger a full reload of the list table view.

When the user returns to the list view controller, the viewDidAppear: method is triggered. In this method I examine the flags and either call

- (void)reloadRowsAtIndexPaths:(NSArray *)indexPaths withRowAnimation:(UITableViewRowAnimation)animation

to reload the specific record if the record was updated, or tell the table view to do a full reload if there is an insert of a new record.

Finally I then remove the list controller as an observer of core data notifications because it is no longer interested.

I don’t know if this is the recommended way to do this, but so far it’s working for me.