Notification callback from BACK button in TableView of SplitViewController

[cybohemia]

I am using a UISplitViewController and I would like to change the view in the DetailArea when the user navigates through different levels in the associated TableView.

Going down a level is easy - when the user selects a row, I can change the view through the didSelectRow: notification.

However, when the user hits the "Back" button in the navigation bar to return to the previous table, I don't know how to get the notification and so don't know when to change the DetailView.

On the iPhone, such a notification wouldn't be needed since there is no split view. However, on an iPad, such a notification would be useful but I'm not sure how to access it or even if it exists.

Has anyone been able to figure out how to respond when a user hits the back button at the navigation bar on top of a table view?

Thanks.

[nobre84]

You have 3 options:
- Use a custom back button and use its action to do what you need (you'll need to use your own graphics if you want the arrow shape of the standard back button)
- Use viewWillDisappear and keep state when you are disappearing forward (didSelect) and backwards (back button)
- If you must really intercept the standard back button and sometimes denying the ability to go back, you must subclass UINavigationController and override navigationBar:shouldPopItem: . I do this to query my controllers if the user is allowed to go back at some places (i.e when they have unsaved changes on the detail view I ask for permission at first before letting they go back)

[cybohemia]

Thanks for the suggestions, nobre84.

I was hoping for the 2nd option so that I wouldn't have to subclass the navigation controller as it is implicitly defined for table views (and automatically takes care of changing the label for the back button to reflect the name of the previous table).

But viewWillDisappear doesn't actually get invoked when a user simply presses the back button on the top of a table view since the table view itself doesn't actually disappear - only its data gets updated.

So I guess I will need to customize things...dang!

Originally Posted by nobre84

You have 3 options:
- Use a custom back button and use its action to do what you need (you'll need to use your own graphics if you want the arrow shape of the standard back button)
- Use viewWillDisappear and keep state when you are disappearing forward (didSelect) and backwards (back button)
- If you must really intercept the standard back button and sometimes denying the ability to go back, you must subclass UINavigationController and override navigationBar:shouldPopItem: . I do this to query my controllers if the user is allowed to go back at some places (i.e when they have unsaved changes on the detail view I ask for permission at first before letting they go back)