ParentViewController is nil no matter what I do

Question

My controller hierachy:

• TabBaseController (UITabBarController)
  • SubclassedController

In my tabbasecontroller I have a navigation bar button, which flips the subclassedcontroller with the presentModalViewController method, to a second UITabBarController.

So my question is: why does not

self.parentViewController

work in the second UITabBarController? It is nil.

I am trying this in my viewDidLoad method in the second UITabBarController:

if (self.parentViewController == nil) {
   NSLog(@"Parent is nil");
}

UPDATED

This is the method in the UITabBarController with the navigationItemButton that presents it

-(IBAction)openModalTabController:(id)sender {  

if (self.nvc == nil) {
    ModalTabController *vc = [[ModalTabController alloc] init]; 
    self.nvc = vc;
    [vc release];
}

[self presentModalViewController:self.nvc animated:YES];
}

This is the controller(UITabBarController) that I present modally:

Header:

@interface NewBuildingViewController : UITabBarController {
}
@end

Main:

@implementation NewBuildingViewController

- (id)init {
[super initWithNibName:nil bundle:nil];

ViewController1 *vc1 = [[ViewController1 alloc] init];
ViewController2 *vc2 = [[ViewController2 alloc] init];
ViewController3 *vc3 = [[ViewController3 alloc] init];

NSArray *controllers = [[NSArray alloc] initWithObjects:vc1, vc2, vc3, nil];

[vc1 release];
[vc2 release];
[vc3 release];

self.viewControllers = controllers;
[controllers release];

self.modalTransitionStyle = UIModalTransitionStyleFlipHorizontal;

return self;
}

 - (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil {
return [self init];
}

@end

I also want to add that this message is displayed in the console(warning) when flipping:

Using two-stage rotation animation. To use the smoother single-stage animation, this application must remove two-stage method implementations. Using two-stage rotation animation is not supported when rotating more than one view controller or view controllers not the window delegate

Answer 1

It would be helpful if you were to show how you are presenting that second UITabBarController. Are you perhaps ignoring the following warning found in the UITabBarController class reference?

When deploying a tab bar interface, you must install this view as the root of your window. Unlike other view controllers, a tab bar interface should never be installed as a child of another view controller.