NSArrayM replaceObjectAtIndex:withObject: object cannot be nil'

Question

I have a project the same menu as this but with submenu that the same slide animation. I create a xib file name it as SecondMenu.xib. The file owner is UIViewController and name it as SecondMenuController. If you check the project REFrosted (check the link), there is DEMOMenuViewController(UIViewController). In method didSelectRowAtIndexPath:. I changed it in my code

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{

    NSMutableArray *controllers = [[NSMutableArray alloc] init];
    for (unsigned i = 0; i < 1; i++) {
        [controllers addObject:[NSNull null]];
    }
    self.viewControllers = controllers;
    SecondMenuController  *controller = [self.viewControllers objectAtIndex:0];

    if ((NSNull *)controller == [NSNull null]) {
        controller = [[SecondMenuController  alloc] initWithNibName:@"SecondMenu" bundle:nil];
        [self.viewControllers replaceObjectAtIndex:0 withObject:controller];

    }

    controller.view.frame = CGRectMake(-self.view.frame.size.width, 0,self.view.frame.size.width,self.view.frame.size.height);

    [self.view addSubview:controller.view];


    [UIView animateWithDuration:0.5 delay:0.0 options:UIViewAnimationOptionCurveEaseInOut animations:^{
        controller.view.frame = CGRectMake(0, 0,self.view.frame.size.width,self.view.frame.size.height);
    } completion:^(BOOL finished) {
        NSLog(@"Done!");
    }];

    //[self hideMenu];

}

That code work for me when connecting to submenu(which is SecondMenuController). In my SecondMenuController, I add a button (this will connect to DEMOHomeViewController, and the storyboard identifier is homeController). here's the code of my button

- (IBAction)buttonConnect:(id)sender {
    DEMONavigationController *navigationController = [self.storyboard instantiateViewControllerWithIdentifier:@"contentController"];

    DEMOHomeViewController *homeViewController = [self.storyboard instantiateViewControllerWithIdentifier:@"homeController"];
    navigationController.viewControllers = @[homeViewController];

    self.frostedViewController.contentViewController = navigationController;
    [self.frostedViewController hideMenuViewController];
}

I get this code in REFrosted before I changed it into my code in didSelectRowAtIndexPath: (as what I have mention above in first code). Why is it I get this error

'NSInvalidArgumentException', reason: '*** -[__NSArrayM replaceObjectAtIndex:withObject:]: object cannot be nil'

I import all files. As what I have understood, when you import a files that connect to the file owner. This means I have control for every method or function that inside of that file when you instantiate it into my SecondMenuController(this only based on my experienced, just rectify me if I'm wrong. I just want to know how the system work). Please see my code. Did I miss something here? Hoping for you advised on how can i fix this or explanation why I get this error.

    DEMONavigationController *navigationController = [self.storyboard instantiateViewControllerWithIdentifier:@"contentController"];

    DEMOHomeViewController *homeViewController = [self.storyboard instantiateViewControllerWithIdentifier:@"homeController"];
    navigationController.viewControllers = @[homeViewController];

Answer 1

2 days of searching an answer for this. I finally get it.

The reason why the DEMOHomeViewController is nil when I click the button because SecondMenuController didn't connect to DEMOHomeViewController even I instantiate it to SecondMenuController class. I learn now. Here's the code

first code that i do. I add this SecondMenuController.h

@property (nonatomic, weak) UIStoryboard * myself;
@property (nonatomic, strong) REFrostedViewController * ref;   
 - (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil myStoryBoard:(UIStoryboard *) xStoryBoard ref: (id) xRef;

In SecondMenuController.m

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil myStoryBoard:(UIStoryboard *) xStoryBoard ref: (id) xRef
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
        self.myself = xStoryBoard;
        self.ref = xRef;
    }
    return self;
}

In my button

DEMONavigationController *navigationController = [self.myself instantiateViewControllerWithIdentifier:@"contentController"];

DEMOSecondViewController *secondViewController = [self.myself instantiateViewControllerWithIdentifier:@"homeController"];

navigationController.viewControllers = @[secondViewController];


self.ref.frostedViewController.contentViewController = navigationController;
    [self.ref.frostedViewController hideMenuViewController];

Now it's working. All you need to do is to call the initWithNibName: method to the DEMOMenuViewController.

Answer 2

The console log means you are attempting to insert nil object in NSArray, which is not allowed. If for some reason you need to add empty object use (NSArray *)[NSNull null] instead.