Swiftgram/submodules/AsyncDisplayKit/docs/_docs/containers-asviewcontroller.md

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ASViewController is a subclass of UIViewController that adds several useful features for hosting ASDisplayNode hierarchies.

An ASViewController can be used in place of any UIViewController - including within a UINavigationController, UITabBarController and UISplitViewController or as a modal view controller.

Benefits of using an ASViewController:

1. Save Memory. An ASViewController that goes off screen will automatically reduce the size of the fetch data and display ranges of any of its children. This is key for memory management in large applications.
2. ASVisibility Feature. When used in an ASNavigationController or ASTabBarController, these classes know the exact number of user taps it would take to make the view controller visible.

More features will be added over time, so it is a good idea to base your view controllers off of this class.

Usage

A UIViewController provides a view of its own. An ASViewController is assigned a node to manage in its designated initializer -initWithNode:.

Consider the following ASViewController subclass, PhotoFeedNodeController, from the ASDKgram example project that would like to use a table node as its managed node.

This table node is assigned to the ASViewController in its -initWithNode: designated initializer method.

SwiftObjective-C

- (instancetype)init
{
  _tableNode = [[ASTableNode alloc] initWithStyle:UITableViewStylePlain];
  self = [super initWithNode:_tableNode];
if (self) {
_tableNode.dataSource = self;
_tableNode.delegate = self;
}
return self;
}

init(models: [Model]) {
  let tableNode = ASTableNode(style: .plain)

  super.init(node: tableNode)

  self.models = models
  
  self.tableNode = tableNode
  self.tableNode.delegate = self
  self.tableNode.dataSource = self
}

Conversion Tip: If your app already has a complex view controller hierarchy, it is perfectly fine to have all of them subclass ASViewController. That is to say, even if you don't use ASViewController's designated initializer -initWithNode:, and only use the ASViewController in the manner of a traditional UIViewController, this will give you the additional node support if you choose to adopt it in different areas your application.