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Update implicit-hierarchy-mgmt.md

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Hannah Troisi
2016-09-06 13:48:51 -07:00
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_docs/implicit-hierarchy-mgmt.md
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@@ -1,26 +1,26 @@
---
title: Implicit Hierarchy Management
title: Automatic Subnode Management
layout: docs
permalink: /docs/implicit-hierarchy-mgmt.html
prevPage: batch-fetching-api.html
nextPage: image-modification-block.html
---
Enabling Implicit Hierarchy Management (IHM) is required to use the <a href="layout-transition-api.html">Layout Transition API</a>. However, apps that don't require animations can still benefit from the reduction in code size that this feature enables.
Enabling Automatic Subnode Management (ASM) is required to use the <a href="layout-transition-api.html">Layout Transition API</a>. However, apps that don't require animations can still benefit from the reduction in code size that this feature enables.
When enabled, IHM means that your nodes no longer require `addSubnode:` or `removeFromSupernode` method calls. The presence or absence of the IHM node _and_ its subnodes is completely determined in its `layoutSpecThatFits:` method.
When enabled, ASM means that your nodes no longer require `addSubnode:` or `removeFromSupernode` method calls. The presence or absence of the ASM node _and_ its subnodes is completely determined in its `layoutSpecThatFits:` method.
### Example ###
<br>
Consider the following intialization method from the PhotoCellNode class in <a href="https://github.com/facebook/AsyncDisplayKit/tree/master/examples/ASDKgram">ASDKgram sample app</a>. This ASCellNode subclass produces a simple social media photo feed cell.
In the "Original Code" we see the familiar `addSubnode:` calls in bold. In the "Code with IHM" (switch at top right of code block) these have been removed and replaced with a single line that enables IHM.
In the "Original Code" we see the familiar `addSubnode:` calls in bold. In the "Code with ASM" (switch at top right of code block) these have been removed and replaced with a single line that enables ASM.
By setting usesImplicitHierarchyManagement to YES on the ASCellNode, we _no longer_ need to call `addSubnode:` for each of the ASCellNode's subnodes. These subNodes will be present in the node hierarchy as long as this class' `layoutSpecThatFits:` method includes them.
By setting .automaticallyManagesSubnodes to YES on the ASCellNode, we _no longer_ need to call `addSubnode:` for each of the ASCellNode's subnodes. These subNodes will be present in the node hierarchy as long as this class' `layoutSpecThatFits:` method includes them.
<div class = "highlight-group">
<span class="language-toggle">
<a data-lang="swift" class="swiftButton">Code with IHM</a>
<a data-lang="swift" class="swiftButton">Code with ASM</a>
<a data-lang="objective-c" class = "active objcButton">Original Code</a>
</span>
<div class = "code">
@@ -64,7 +64,7 @@ By setting usesImplicitHierarchyManagement to YES on the ASCellNode, we _no long
self = [super init];
if (self) {
<b>self.usesImplicitHierarchyManagement = YES;</b>
<b>self.automaticallyManagesSubnodes = YES;</b>
_photoModel = photo;
@@ -94,7 +94,7 @@ By setting usesImplicitHierarchyManagement to YES on the ASCellNode, we _no long
Several of the elements in this cell - `_userAvatarImageNode`, `_photoImageNode`, and `_photoLocationLabel` depend on seperate data fetches from the network that could return at any time. When should they be added to the UI?
IHM knows whether or not to include these elements in the UI based on the information provided in the cell's ASLayoutSpec.
ASM knows whether or not to include these elements in the UI based on the information provided in the cell's ASLayoutSpec.
<div class = "note">
An `ASLayoutSpec` completely describes the UI of a view in your app by specifying the hierarchy state of a node and its subnodes. An ASLayoutSpec is returned by a node from its <code>