UITableView Delegate in Sub Viewcontroller

Question

I have a UIViewController call Parent, and I have a UIView subview within Parent. I want to add one of two different possible UIViewControllers, called A and B, as subviews of Parent. A is a UIViewController with a UITableView. I set the datasource and delegate of the UITableView in A to A.

I can then "successfully" add A to Parent, setting the data for A as follows:

    AViewController *vc = (AViewController *)[self.storyboard instantiateViewControllerWithIdentifier:@"A"];
    NSMutableArray *data = [@[@"foo",@"bar",@"baz"] mutableCopy];
    vc.posts = data;
    [self.container addSubview:vc.view];

By successful, I mean that I see the tableview with the correct data in the cells. Namely foo, bar, and baz as the rows.

My Problem: When I try to scroll the tableview, it crashes. When I try to select a cell, I get the following exception:

Terminating app due to uncaught exception 'NSInvalidArgumentException',
reason: '-[_UIAppearanceCustomizableClassInfo
tableView:didSelectRowAtIndexPath:]: unrecognized selector sent to instance 0x78c64430'

Answer 1

Because the AViewController is declared locally in your code above, it is deallocated as soon as that code completes. So when you touch for scrolling/selection and the delegate/datasource methods are called, the delegate and datasource point to a completely different object (or none at all). Hence your crash.

Furthermore, when implementing customer container views you need to implement some code so both parent and child know. Take a look at "Implementing a Custom Container View Controller" in the Apple Docs:

    [self addChildViewController:vc];
    [self.container addSubview:vc.view];
    [vc didMoveToParentViewController:self];

I believe the addChildViewController will also provide a strong reference from the parent to the child (vc), thereby preventing it from being deallocated. So the above code should fix the deallocation problem as well.