> 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/xamarin/guides/ios/bookmark/outline.md).

# Outline tree (iOS)

Learn how to work with an outline tree in Xamarin.iOS using a UI component or API guide. Display outlines & bookmarks, navigate through documents, and create new bookmarks programmatically. The Apryse

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 in Xamarin.iOS

{% hint style="info" %}
**This tutorial only applies to Xamarin.iOS. See Xamarin.Android equivalent here .**
{% endhint %}

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/xamarinios/tools/api/pdftron.PDF.Controls.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/xamarinios/tools/api/pdftron.PDF.PDFViewCtrl.html) by tapping on a bookmark item.

![](https://653871032-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FgjsBtuYmcKhWOdM9VCg4%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*](/xamarin/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:

{% code lineNumbers="true" %}

```csharp
var outlineViewController = new pdftron.PDF.Controls.PTOutlineViewController (mPdfViewCtrl);
outlineViewController.OutlineViewControllerOutlineSelected += (sender, e) => {
  // perform custom action
    this.DismissViewController (true, null);
};
outlineViewController.OutlineViewControllerDidCancel += (object sender, EventArgs e) => {
  this.DismissViewController (true, null);
};

var navigationController = new UINavigationController (outlineViewController);

if (UserInterfaceIdiomIsPad)
{
    navigationController.ModalPresentationStyle = UIModalPresentationStyle.Popover;
    navigationController.PopoverPresentationController.BarButtonItem = outlineButton;
}

this.PresentViewController (navigationController, true, null);
```

{% endcode %}

{% 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 [`PopoverPresentationController`](https://docs.microsoft.com/en-us/dotnet/api/uikit.uipopoverpresentationcontroller) with either:

* a [`SourceRect`](https://docs.microsoft.com/en-us/dotnet/api/uikit.uipopoverpresentationcontroller.sourcerect#UIKit_UIPopoverPresentationController_SourceRect) AND
* a [`SourceView`](https://docs.microsoft.com/en-us/dotnet/api/uikit.uipopoverpresentationcontroller.sourceview#UIKit_UIPopoverPresentationController_SourceView)

OR

* a [`BarButtonItem`](https://docs.microsoft.com/en-us/dotnet/api/uikit.uipopoverpresentationcontroller.barbuttonitem#UIKit_UIPopoverPresentationController_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, edit & create outlines / bookmarks

To navigate an outline tree and print its result.

{% code lineNumbers="true" %}

```csharp
void PrintIdent(Bookmark item)
{
  int ident = item.GetIdent() - 1;
  for (int i=0; i < ident; ++i) {
    Console.Write("  ");
  }
}
void PrintOutlineTree(Bookmark item)
{
  for (; item.IsValid(); item=item.GetNext()) {
    PrintIdent(item);
    Console.Write("{0:s}{1:s} ACTION -> ", (item.IsOpen() ? "- " : "+ "), item.GetTitle());
    if (item.HasChildren()) {
      PrintOutlineTree(item.GetFirstChild());
    }
  }
}
PDFDoc doc = new PDFDoc(filename);
Bookmark root = doc.GetFirstBookmark();
PrintOutlineTree(root);
```

{% endcode %}

[Read, add, edit PDF outlines and bookmarks](/xamarin/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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