> 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/viewer/viewer/new-ui-migration.md).

# Migrate to the New Viewer UI

Learn how to easily migrate to the new UI in your app with a few simple steps. Update libraries, migrate PdfViewCtrlTabHostFragment, and customize your theme for a seamless transition. The Apryse Xama

If you have integrated the document viewer previously in your app (i.e. [`DocumentActivity`](/xamarin/guides/android/basics/open.md#activity) or [`PdfViewCtrlTabHostFragment`](/xamarin/guides/android/basics/open.md#fragment)), you can easily migrate to use the new UI with a couple of simple steps.

## Prerequisites

* Updated Apryse libraries to version 8.0.0 (see [changelog](/xamarin/changelogs/version-8/v8-0-0.md) for more info)

## Migrate PdfViewCtrlTabHostFragment

1. Update all references to `ViewerBuilder` to `ViewerBuilder2`. This new builder will create the new viewer fragment [`PdfViewCtrlTabHostFragment2`](https://sdk.apryse.com/api/xamarinandroid/tools/api/pdftron.PDF.Controls.PdfViewCtrlTabHostFragment2.html), which contains the new UI.
2. Update all references to `PdfViewCtrlTabHostFragment` to `PdfViewCtrlTabHostFragment2` in your project.
3. Update all references to `PdfViewCtrlTabFragment` to [`PdfViewCtrlTabFragment2`](https://sdk.apryse.com/api/xamarinandroid/tools/api/pdftron.PDF.Controls.PdfViewCtrlTabFragment2.html) in your project.
4. (Optional) If you have defined the `CustomAppTheme` style to customize your theme, you will need to change this style to extend `PDFTronAppTheme` and pass it into `ViewerBuilder2` as described in our customize viewer theme guide.

## Migrate DocumentActivity

1. Remove any calls to `DocumentActivity.openDocument(...)`.
2. Then launch the activity using `DocumentActivity.IntentBuilder` as described in this guide.
3. If you have defined the `CustomAppTheme` style to customize your theme, you will need to change this style to extend `PDFTronAppTheme`.


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