Crashing when adding custom view controllers to UITabBarController

Question

My iOS 6 application recently started crashing when adding custom view controllers to a UITabBarController.

My AppDelegate has public properties

@property (readwrite, strong) UITabBarController *TabBarController;
@property (readwrite, strong) ViewControllerTypeA *ViewControllerA;  //extends UIViewController Class
@property (readwrite, strong) ViewControllerTypeB *ViewControllerB;  //extends UIViewController Class
@property (readwrite, strong) ViewControllerTypeC *ViewControllerC;  //extends UIViewController Class

Initially, I create a tab bar controller, and add the view controllers to this:

- (void)InitializeTabBar {

[self setTabBarController:[[UITabBarController alloc] init]];
UITabBarItem *Tab1 = [[UITabBarItem alloc] init];
UITabBarItem *Tab1 = [[UITabBarItem alloc] init];
UITabBarItem *Tab2 = [[UITabBarItem alloc] init];

[self setViewControllerA:[[ViewControllerTypeA alloc] init]];
[self setViewControllerB:[[ViewControllerTypeB alloc] init]];
[self setViewControllerC:[[ViewControllerTypeC alloc] init]];

[[self ViewControllerA] setTabBarItem:Tab1];
[[self ViewControllerB] setTabBarItem:Tab2];
[[self ViewControllerC] setTabBarItem:Tab3];

[[self TabBarController] setViewControllers:@[[self ViewControllerA],[self ViewControllerB],[self ViewControllerC]] animated:NO];

}

And it crashes on the last line with error:

Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: ' -[__NSPlaceholderDictionary initWithObjects:forKeys:count:]: attempt to insert nil object from objects[1]'

However, if I instead insert default UIViewController Classes, i.e.:

[[self TabBarController] setViewControllers:@[[[UIViewController alloc] init],[[UIViewController alloc] init],[[UIViewController alloc] init]] animated:NO];

Everything then loads perfectly. What am I doing wrong?

Try this, NSArray *multipleViewControllers=[[NSArray alloc] initWithObjects:[self ViewControllerA],[self ViewControllerB],[self ViewControllerC],nil]; [self.tabBarController setViewControllers:multipleViewControllers]; — karthika
check whether you are doing anything wrong in viewDidLoad or loadView or viewWillAppear method of your custom controller, because your code looks perfect. — Prasad Devadiga
Put the exceptional break point and check where exactly it is crashing. — Prasad Devadiga
Thanks, this appears correct - it is crashing in the viewDidLoad method. The line on which it crashing is the creation of a view controller: "[[[self NavigationController] view] setFrame:CGRectMake(0,-20,ScreenWidth,ScreenHeight - (ControllerHeightOffset+29))];" Unfortunately this confuses me just as much! — Stuart Barth

Andrea Andrea · Accepted Answer · 2013-09-20T05:58:41

The problem probably is that you are trying to insert a nil object into a dictionary, since there are no dictionary around here, it could be something inside the cycle of the first view controller.

Crashing when adding custom view controllers to UITabBarController

2 Answers