Multiple root view controllers for UINavigationController?

Question

I'm trying to switch between several table views as the root of a navigation controller. Depending on the settings of my app, I want to use different sets of data with different methods, and prefer to have these encapsulated in separate classes.

My thought was to set a view manager class (UIViewController) as the root view controller of the navigation controller. In the view manager we check the settings to see which view we want to load:

if([application_mode intValue]==APPLICATION_MODE_A){
    AViewController *aView = [[DeviceTableViewController alloc] init];
    [self.view insertSubview:aView.view atIndex:0];
}
else if([application_mode intValue]==APPLICATION_B){
    BViewController *bView = [[BViewController alloc] init];
    [self.view insertSubview.bView.view atIndex:0];
}

That does in fact insert the appropriate view into the view manager, at the cost of a white bar at the top of the inserted view and no info on the navigation bar, ie the subview is not connected to the navigation controller.

What's the proper way to do this? I'd really prefer not to have one ginormous table view!

Answer 1

Where do you set your navigationController's rootViewController? Can't you just set it to an AviewController's object or an BViewController's object at this time ? You may not need an intermediate UIViewController

I would do at the beginning :

//navigationController comes from a Xib or previous code
if([application_mode intValue]==APPLICATION_MODE_A){
    AViewController *aView = [[DeviceTableViewController alloc] init];
    navigationController.rootViewController = aView;
    [aView release];
}
else if([application_mode intValue]==APPLICATION_B){
    BViewController *bView = [[BViewController alloc] init];
    navigationController.rootViewController = bView;
    [bView release];
}

Answer 2

Since there is no view controller containment, I like the approach outlined in Jonah William's blog:

http://blog.carbonfive.com/2011/03/09/abusing-uiviewcontrollers/

You can't effectively place a view controller inside another; instead, we create something with similar lifecycle methods (viewDidLoad, viewDidAppear, etc) and forward those methods from the parent to the child. This 'psudo-viewcontroller' has a view property that we add as a subview to the parent's view, using UIView addSubView

http://developer.apple.com/library/ios/#documentation/uikit/reference/UIView_Class/UIView/UIView.html#//apple_ref/occ/instm/UIView/addSubview:

With this approach, we can encapsulate view elements, switch them out dynamically in a view controller, place several within a single view controller, etc. This way they can be considered separately from your navigation stack. It's a bit of work, but the cleanest UI encapsulation approach in iOS 4 in my opinion.