Question

I have a fairly simple iPhone application that I want to have run on both the iPhone and the iPad. I’d like to just have the iPad version be a bigger version of the iPhone version, scaled up or not — I’m working on an iPad-specific version of the app that makes better use of the interface, but wanted to make sure my existing customers have something in the meantime.

The app is a simple tab-based application, and within each tab is a navigation controller that presents a table view, each of which can drill down a couple of layers. Everything mostly works — I have a couple of instances of views not filling the space available, but I can fix that. My biggest problem right now is that the navigation controllers universally break when I try using them. Once I drill down a level or two, I suddenly won’t be able to come back up again.

Let me try to explain in more detail:

One tab starts off with a “year” table view, showing all years that have entries; if you tap a year, it pushes another table view with all months in that year that have entries; if you tap a month, it pushes another table view that shows the individual entries; if you tap an entry, it pushes a view (a UIWebView, with some extra widgets) that shows an entry’s details.

Each push is done with [self.navigationController pushViewController: foo animated: YES]. The three table view controllers I mentioned above are all created from the same nib (in fact, everything pushed onto a navigation controller in any tab is loaded from the same nib). Since I know there are only up to three levels of navigation, I just allocated three identical view controllers and use one, two, or three depending on how many entries there are.

Popping these controllers off using the “back” button seems to universally mess up the state of the view controller. So, if I drill down to the third view — showing everything in a single month — I won’t be able to pop all the way back up to the first view: the back button stops working if I pop up one level.

Another example in another tab: it’s one table view that you can tap any entry on, and a new view controller will be pushed that shows the details of that entry. If I tap an entry, tap the back button, then tap the entry again, no back button appears, or sometimes, the text that would go inside the back button appears, but no button appears!

This behavior happens if I try running the iPhone app in scaled mode (built with base SDK 4.0, supporting OS 3.2) or in native mode (built with base SDK 3.2). It runs without problems on the iPhone. I’m kind of at a loss here, because this stuff always “just worked” out of the box, mostly from the defaults that were set up back when I first created the project.

My programmer’s instincts are telling me that I’m doing something very wrong in my view navigation, and that the iPad is just exposing it, but I can’t figure out what it is.

Has anyone run into an issue like this, or suggest something it might be or some better way to debug what’s going on?

Answer 1

The issue was that I had a category on NSMutableArray, which added stack-like methods push and pop. Removing this category class fixed this issue.

WTF, though.