Question

I have a very basic container view that contains a sidebar and swaps out the view controllers in the content area (think UISplitView but with a small icon sidebar / vertical UITabBar).

The container view controller uses autoLayout and resizes correctly when rotated.
Content viewController 1 uses autolayout and was made with IB, so it has a xib file.
Content viewController 2 inherits from UITableViewController and does not use a xib.

If I assign viewController 1 as the root view controller and rotate, the resize works and here are the callbacks that I get in viewController 1:

• willRotateToInterfaceOrientation
• updateViewConstraints
• viewWillLayoutSubviews
• didRotateFromInterfaceOrientation

However, if I assign my container view controller as the root view controller, load viewController 1 and rotate, the resize does not work. And I only get the following callbacks inside viewController 1:

• willRotateToInterfaceOrientation
• didRotateFromInterfaceOrientation

Inside my view controller container, here’s how I swap the view controllers:

[self addChildViewController:toViewController];
[toViewController didMoveToParentViewController:self];

// Remove the old view controller
[fromViewController willMoveToParentViewController:nil];
[fromViewController.view removeFromSuperview];
[fromViewController removeFromParentViewController];

// Add the new view
[self.contentContainerView addSubview:toViewController.view];

Now, I do get the callbacks that a rotation is about to happen, but it seems as if neither updateViewConstraints nor viewWillLayoutSubviews is called. This explains why the resize is not happening, but why are those methods not called once I put the view controller in a container view?

I also tried to explicitly return YES in my container on both

shouldAutomaticallyForwardAppearanceMethods

and

shouldAutomaticallyForwardAppearanceMethods

although this should be the default already.

Also, the view controller not made with IB (view controller 2) resizes correctly when rotating inside the container. However, I don’t explicitly use NSLayoutConstraints on this one, so I suspect it’s defaulting to Springs and Struts for the resizing when rotating.

Do I need to forward some other events on my view controller container to get the auto layout view controller to resize correctly when rotating?

Answer 1

OK, I think I was missing this method here in my view controller container:

- (void)willAnimateRotationToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation duration:(NSTimeInterval)duration {
    self.contentViewController.view.frame = self.contentContainerView.bounds;
}

While this resizes now correctly when rotating, it still doesn’t trigger

updateViewConstraints

in my child view controller. Interesting