UITableViewController subclass implements UIDataSourceModelAssociation protocol but its methods are never called

Question

My app uses the Stanford course's CoreDataTableViewController, which is a subclass of UITableViewController.

For particular views of my app I create subclasses of CoreDataTableViewController to manage a particular view.

I've just recently hooked up state encode and restoration throughout most of my app and it all seems to be working ok. The only thing I've left late is implementing the UIDataSourceModelAssociation protocol to allegedly preserve visible and selected rows of UITableViews (I was also hoping it may preserve the editing state of the table view, and of a particular row if I've selected it to delete, but haven't confirmed yet).

I implemented the UIDataSourceModelAssociation within CoreDataTableViewController hoping that it would just then work for all my views, but on debugging it the feature doesn't work, and adding breakpoints I see that neither of the two UIDataSourceModelAssociation methods are ever called when i put my app into the background with the home button, or restore it cold by re-running in XCode.

CoreDataTableViewController and my subclasses of it implement some dataSource methods to actually display the rows in my table view. I've searched around and found that UITableViewController automatically adds itself as the dataSource for the tableView.

I've added sanity asserts in my subclasses viewDidLoad functions of the form

assert(self.tableView);
assert(self.tableView.dataSource == self); <--- fails here

Which fails on checking the dataSource being ourselves. I can see by logging and using the debugger that the dataSource is non-nil at this point.

I guess I just wondered whether when we subclass a class does each class share the same self value, or is it because my UITableViewController has set itself to be the dataSource, but by the time I've subclassed it twice down to my particular view instance it's self is slightly different than the parent UITableViewController. Or is something else intercepting the dataSource and forwarding on as required. As a fix should I consider hardcoding my own subclass to self, or have the CoreDataTableViewController add itself as the dataSource explicitly as this is where the UIDataSourceModelAssociation methods are implemented.

For reference my view hierarchy consists of my UITableViewController subclassed views living inside NavigationControllers which I've heard may cause issues.

Just a little of clarity on how subclassing should work with respect to self pointers across the classes and wondering if anyone could figure out why my protocol methods aren't being called would be really appreciated.

Cheers

Answer 1

I'm still not sure why my tableViewController's dataSource isn't directly set to self. But clearly my dataSource methods are called as my tableView functions. Obviously some sort of object is forwarding on dataSource methods to my actual class for me...

In the end getting the UIDataSourceModelAssociation protocol methods to be called was as simple as ensuring that both the UITableViewController and the UITableView within it had restoration ids.. with just the outer UITableViewController having a restoration id, none of these methods are called.

Sadly now I'm scuppered by these methods being called before my UIManagedDocument has finished loading so I cannot actually do anything useful within them. That's another problem though.