ios - 为什么我在设备上出现数组异常但在模拟器中却没有？

Question

'NSInvalidArgumentException'，原因：'-[__NSCFSet addObject:]：尝试插入 nil'

当我运行下面的代码时，为什么我在 iPhone 5.1 而不是在 6.0 模拟器中得到这个异常？此代码用于幻灯片视图控制器，5.1 支持吗？

- (NSArray*)controllers {
    NSMutableArray *result = [NSMutableArray array];
    if (self.centerController) [result addObject:self.centerController];
    if (self.leftController) [result addObject:self.leftController];
    if (self.rightController) [result addObject:self.rightController];
    if (self.topController) [result addObject:self.topController];
    if (self.bottomController) [result addObject:self.bottomController];
    return [NSArray arrayWithArray:result];
}

我认为这就是凯文正在寻找的。

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];

IIViewDeckController* deckController = [self generateControllerStack];
self.leftController = deckController.leftController;
self.centerController = deckController.centerController;

/* To adjust speed of open/close animations, set either of these two properties. */
// deckController.openSlideAnimationDuration = 0.15f;
// deckController.closeSlideAnimationDuration = 0.5f;

self.window.rootViewController = deckController;
[self.window makeKeyAndVisible];
return YES;
}

- (IIViewDeckController*)generateControllerStack {
LeftViewController* leftController = [[LeftViewController alloc] initWithNibName:@"LeftViewController" bundle:nil];
RightViewController* rightController = [[RightViewController alloc] initWithNibName:@"RightViewController" bundle:nil];

UIViewController *centerController = [[ViewController alloc] initWithNibName:@"ViewController" bundle:nil];
centerController = [[UINavigationController alloc] initWithRootViewController:centerController];
IIViewDeckController* deckController =  [[IIViewDeckController alloc] initWithCenterViewController:centerController
                                                                                leftViewController:leftController
                                                                               rightViewController:rightController];
deckController.rightSize = 100;

[deckController disablePanOverViewsOfClass:NSClassFromString(@"_UITableViewHeaderFooterContentView")];
return deckController;
}