在另一个modalView上呈现ViewController

Question

我在导航控制器上显示的另一个modalView(B)上展示了modalView(A)。

问题在于dealloc modalView(A)方法永远不会被调用，并且应用程序在从NSUserDefaults获取时会崩溃。

我无法弄清楚究竟是什么问题？

编辑： -

代码

ViewControllerA * aViewController = [[ViewControllerA alloc] initWithNibName:@"ViewControllerA" bundle:[NSBundle mainBundle]];
UINavigationController *navController = [[UINavigationController alloc] initWithRootViewController: aViewController];
navController.navigationBar.barStyle = UIBarStyleBlack;
[self presentViewController:navController animated:YES completion:^{}];
[aViewController release];
[navController release];

modalView（B）

ViewControllerB *bViewController = [[ViewControllerA alloc] initWithNibName:@"ViewControllerA" bundle:[NSBundle mainBundle]];
[self presentViewController: bViewController animated:YES completion:^{}];  
[bViewController release];