iOS: NSInternalInconsistencyException When Seguing to New View Controller - ios

Question

If a core data check is empty, I want to leave a certain view controller and segue to a different view controller.
The core data check is called from View WIllAppear.
Right now, I have the command to make the transition at the end of the core data pull. If the pull comes back empty ,then I trigger the code to segue to another view controller.
This is causing a problem since the page is not yet loaded when I ask IOS to go to a different page. However, I really don't want to the page to load first.
Also, I don't want to move this code out of viewWillAppear, for example, to viewDidLoad as I want to do a fresh check of the data every time someone visits the screen.
Can anyone suggest right way to do this?
Here is my code:
In viewWillAppear:
[self updateInterface];
In updateInterface:
self.item = [self getLatestItem:userid inManagedObjectContext:_managedObjectContext];
in getLatestItem
NSArray *matches = [_managedObjectContext executeFetchRequest:request error:&error];
if (!matches ||[matches count]<1) {
// handle error
self.noNewItems=1;
[self gotoListChallenges];
} else {
NSLog(#"got at least one match");
item = [matches lastObject];
}
return item;
}
- (void) gotoListItems {
UIStoryboard *storyBoard = self.storyboard;
listItemsVC *listVC =
[storyBoard instantiateViewControllerWithIdentifier:#"listItems"];
UINavigationController *nav = [[UINavigationController alloc] initWithRootViewController: listVC];
[self presentModalViewController:nav animated:YES];
}