> For the complete documentation index, see [llms.txt](https://docs.apryse.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.apryse.com/ios/bookmarks/outline.md).

# Outline tree

Discover how to work with an outline tree using a UI component or API guide. Display outlines & bookmarks on iOS, navigate through PDF documents, and create new bookmarks programmatically. Learn more

There are two options to working with an outline tree. First is using a UI component that provides tools to set a bookmark or display the outline. Second is an API guide to programmatically read outline items.

{% tabs %}
{% tab title="UI component" %}

## Display outlines & bookmarks on iOS

A document outline, or table of contents, demonstrates how the PDF document is organized and helps users see the overall picture. The [`PTOutlineViewController`](https://sdk.apryse.com/api/ios/Classes/PTOutlineViewController.html) class shows the document outline (table of contents) that can be used to navigate through the document being viewed by a [`PTPDFViewCtrl`](https://sdk.apryse.com/api/ios/Classes/PTPDFViewCtrl.html) by tapping on a bookmark item.

![](https://4149080208-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FgY6xtY9ZQd9XMpvWlGM0%2Fuploads%2Fgit-blob-9acb375f71cdbf76d2250227df451bef01effd66%2Fa400d02a39898855332fc3a1d2b17effe42eb9a7-1242x2208.png?alt=media)

*The outline control is part of the Tools library, so make sure you have* [*added the Tools library to your project*](/ios/ui-customization/setup.md)*.*

## Show an outline view controller

To create a new outline view controller instance and display it from another view controller, supply a `PTPDFViewCtrl` instance to the `PTOutlineViewController` designated initializer:

{% tabs %}
{% tab title="Swift" %}
{% code lineNumbers="true" %}

```swift
// Initialize outline view controller with a PTPDFViewCtrl instance.
let outlineViewController = PTOutlineViewController(pdfViewCtrl: pdfViewCtrl)

// Set the current view controller as the outline view controller's delegate.
outlineViewController.delegate = self

let navigationController = UINavigationController(rootViewController: outlineViewController)
if ( UIDevice.current.userInterfaceIdiom == .pad ) {
    navigationController.modalPresentationStyle = .popover
    navigationController.popoverPresentationController?.barButtonItem = outlineButton
}

self.present(navigationController, animated: true, completion: nil)
```

{% endcode %}
{% endtab %}

{% tab title="Obj-C" %}
{% code lineNumbers="true" %}

```objc
// Initialize outline view controller with a PTPDFViewCtrl instance.
PTOutlineViewController *outlineViewController = [[PTOutlineViewController alloc] initWithPDFViewCtrl:pdfViewCtrl];

// Set the current view controller as the outline view controller's delegate.
outlineViewController.delegate = self;

UINavigationController *navigationController = [[UINavigationController alloc] initWithRootViewController:outlineViewController];
if ( [[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPad ) {
    navigationController.modalPresentationStyle = UIModalPresentationPopover;
    navigationController.popoverPresentationController.barButtonItem = self.outlineButton;
}

[self presentViewController:navigationController animated:YES completion:nil];
```

{% endcode %}
{% endtab %}
{% endtabs %}

{% hint style="info" %}
**The outline view controller must be pushed onto a navigation controller's stack before being shown.**
{% endhint %}

{% hint style="info" %}
**Presenting on iPads:**

The outline view controller is designed to be presented in a popover on iPads. To do so, you must provide the `PTOutlineViewController`'s [`UIPopoverPresentationController`](https://developer.apple.com/uikit/uipopoverpresentationcontroller/) with either:

* a [`sourceRect`](https://developer.apple.com/uikit/uipopoverpresentationcontroller/1622324-sourcerect/) AND
* a [`sourceView`](https://developer.apple.com/uikit/uipopoverpresentationcontroller/1622313-sourceview/)

OR

* a [`barButtonItem`](https://developer.apple.com/uikit/uipopoverpresentationcontroller/1622314-barbuttonitem/)

as in the example above.
{% endhint %}

You can set a delegate to be notified by the outline view controller when outline bookmarks are selected with the `PTOutlineViewControllerDelegate` protocol. (See the CompleteReader example for usage of an `PTOutlineViewController`.)
{% endtab %}

{% tab title="API guide" %}

## API to programmatically read & create outlines / bookmarks

To navigate an outline tree and print its result.

{% tabs %}
{% tab title="Obj-C" %}
{% code lineNumbers="true" %}

```objc
void PrintIndent(PTBookmark *item) 
{
	int ident = [item GetIndent] - 1;
	for (int i=0; i<ident; ++i) {
    printf("  ");
  }
}
void PrintOutlineTree(PTBookmark *item)
{
	for (; [item IsValid]; item=[item GetNext]) {
		PrintIndent(item);
		if ([item IsOpen]) {
			printf("- %s ACTION -> ", [[item GetTitle] UTF8String]);
		}
		else {
			printf("+ %s ACTION -> ", [[item GetTitle] UTF8String]);
		}
		if ([item HasChildren]) {
			PrintOutlineTree([item GetFirstChild]);
		}
	}
}
PTPDFDoc *doc = [[PTPDFDoc alloc] initWithFilepath: filename];
PTBookmark *root = [doc GetFirstBookmark];
PrintOutlineTree(root);
```

{% endcode %}
{% endtab %}

{% tab title="Swift" %}
{% code lineNumbers="true" %}

```swift
func PrintIndent(item: PTBookmark) -> String {
  let indent = item.getIndent() - 1
  var i = 0
  var str = ""
  while i < indent {
    str = str + ("  ")
    i += 1
  }
  return str
}
func PrintOutlineTree(item: PTBookmark) {
  var currentItem = item
  while currentItem.isValid() {
    let indent: String = PrintIndent(item: currentItem)
    if currentItem.isOpen() {
      print("\(indent)- \(currentItem.getTitle()!) ACTION -> ")
    }
    else {
      print("\(indent)+ \(currentItem.getTitle()!) ACTION -> ")
    }
    if currentItem.hasChildren() {
      PrintOutlineTree(item: currentItem.getFirstChild())
    }
    currentItem = currentItem.getNext()
  }
}
let doc: PTPDFDoc = PTPDFDoc(filepath: filename)
let root: PTBookmark = doc.getFirstBookmark()
PrintOutlineTree(item: root)
```

{% endcode %}
{% endtab %}
{% endtabs %}

[Read, add, edit PDF outlines and bookmarks](/ios/get-started/samples.md#bookmarks) Full code sample which illustrates how to read and edit existing outline items and create new bookmarks using the high-level API.

## About outline tree

A PDF document may display a document outline on the screen, allowing the user to navigate interactively from one part of the document to another. The outline consists of a tree-structured hierarchy of Bookmarks (sometimes called outline items), which serve as a "visual table of contents" to display the document's structure to the user.

Each Bookmark has a title that appears on screen, and an Action that specifies what happens when a user clicks on the Bookmark. The typical Action for a user-created Bookmark is to move to another location in the current document — although any Action can be specified.
{% endtab %}
{% endtabs %}


---

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