UINavigationController不会在推送的UIViewController上调用viewDidLoad

Question

I'm facing an odd problem concerning pushing a UIViewController into a UINavigationController. CustomTableViewController is a subclass of UITableViewController

CustomTableViewController* vc = [[CustomTableViewController alloc] initWithStyle:UITableViewStylePlain];
UINavigationController *navVC = [[UINavigationController alloc] initWithRootViewController:vc];
[self.view addSubview:navVC.view];

For some reason, the Navigation Controller is loaded and visible on screen but viewDidLoad is never called on CustomTableViewController .

Manually pushing the VC afterwards also does not work (still not loading the vc 's view)

• [navVC pushViewController:vc animated:YES];

However, the following methods DO call viewDidLoad on vc :

1. [self.view addSubview:vc.view];
2. [self presentViewController:navVC animated:YES completion:nil];
3. [self presentViewController:vc animated:YES completion:nil];

So I tend to believe that there is nothing wrong with the View Controller nor the Navigation Controller. However, I have no clue why the view is not being loaded. Manually forcing [vc view] will load the view but then the other view lifecycle methods are not called.

There is also nothing wrong with CustomTableViewController , as using UITableViewController itself also doesn't work.

Any ideas?

Answer 1

You need to add it as child view controller

    [childController willMoveToParentViewController:rootViewController];
    [rootViewController addChildViewController:childController];
    [rootViewController.view addSubview:childController.view];
    [childController didMoveToParentViewController:rootViewController];

Hope this works

Answer 2

I suspect you're getting issues because it seems you are trying to make a custom container view controller.

Read up on Apple's guide on custom container view controllers.

From the guide, here are some example methods to add and remove child view controllers:

Swift 3.0:

func display(contentController content: UIViewController) {
    addChildViewController(content)

    // Here, frameForContentController is just some function you define
    // that calculates and returns the frame of the content controller's view.
    content.view.frame = frameForContentController()

    view.addSubview(content.view)
    content.didMove(toParentViewController: self)
}

func hide(contentController content: UIViewController) {
    content.willMove(toParentViewController: nil)
    content.view.removeFromSuperview()
    content.removeFromParentViewController()
}

Objective-C:

- (void)displayContentController:(UIViewController *)content
{
   [self addChildViewController:content];

   // Here, [self frameForContentController] is just some method you define
   // that calculates and returns the frame of the content controller's view.
   content.view.frame = [self frameForContentController];

   [self.view addSubview:content.view];
   [content didMoveToParentViewController:self];
}

- (void)hideContentController:(UIViewController *)content
{
   [content willMoveToParentViewController:nil];
   [content.view removeFromSuperview];
   [content removeFromParentViewController];
}