What’s New for Xamarin Developers in Visual Studio 2019 version 16.4

Pierce Boggan

This week, Visual Studio 2019 version 16.4 was released with many improvements for mobile developers in Visual Studio. This release brings major productivity enhancements including the GA release of XAML Hot Reload for Xamarin.Forms, smaller Android APKs, tooling to migrate your applications to Android X, and numerous performance and reliability improvements. All developers can also take advantage of enhancements to Visual Studio 2019 in version 16.4 including pin-able properties in the debugger, IntelliSense support for XAML snippets, and new C# refactoring capabilities.

Install Visual Studio 2019 version 16.4

Let’s take a look at what you can find in this release.

XAML Hot Reload for Xamarin.Forms

XAML Hot Reload for Xamarin.Forms is now generally available (GA), enabling you to make changes to your XAML UI and see them reflected live, without requiring another build and deploy.

XAML Hot Reload for Xamarin.Forms speeds up your development and makes it easier to build, experiment, and iterate on your user interface. You no longer have to rebuild your app each time you tweak your UI – it instantly shows you your changes in your running app.

Because your application is compiled using XAML Hot Reload, it works with all libraries and third-party controls, is available for iOS and Android, and works on all valid deployment targets, including simulators, emulators, and physical devices. For more information, check out the XAML Hot Reload for Xamarin.Forms documentation.

Android App Bundle Publishing

We heard your feedback that you wanted smaller Android APKs. With Visual Studio 2019 version 16.4, we have introduced support for the Android App Bundle publishing format. App Bundles provide users with with optimized APKs per their device specifications when downloading an app from the Google Play Store or various Android App Stores.

You no longer need to worry about certain types of resource qualifiers like locale, screen orientation, and pixel density being included in the APK resulting in bloat to your APK. Alongside that, App Bundles only include ABIs the device supports. With Android App Bundles, the final APK delivered to the user’s device only contains the minimal APK required for the application to run on device. Reducing your APK size also has additional compounding benefits, including faster application load, memory consumption, power consumption, and much more.

For more information on Android App Bundles, check out the Xamarin Show or documentation:

Android X Migration Wizard

The Android Support Library has had a long history of over the last 7 years providing backwards compatibility to Android framework APIs. Over the years, this library has grown in adoption as the majority of Android apps in the Google Play Store use the Support Library in some fashion today. AndroidX packages are the next generation of Android Support Libraries which includes simplified package names to better reflect each package’s content and it’s supported API levels. Because AndroidX is a redesign of the Android Support Library, it includes migration steps that will affect Android applications built with the Android Support Library.

To help make this migration experience as smooth as possible, in Visual Studio 2019 version 16.4 we are introducing a new migration wizard from the Android Support Libraries to AndroidX. You can enable this experimental feature by going to Tools > Options > Xamarin > Android Settings and selecting Enable AndroidX Migrator (Experimental):

Enable the AndroidX migration wizard.

To learn more about AndroidX, check out the Xamarin Show and blog:

Wrapping Up

This is just a quick glance at all the improvements now available in Visual Studio 2019 version 16.4 for Xamarin developers. We love to hear inspiring ideas of ways to improve Visual Studio 2019. Please take all questions and suggestions to Developer Community as this is where teams interact the most.

Give Suggestions & Feedback on Developer Community

Your feedback drives our product roadmap, so be sure to make your voice heard!


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  • Mark Dev 0

    Hi ,
    Great stuff. I am really interested in the aab package. Once I have chosen aab from the dropdown in visual studio for my release , what do I need to do to integrate in my azure devops pipeline. Is there a task for the azure devops, or some instructions. I guess the sign apk task is redudant..

    Any blogs anywhere/Instructions for azure devops integration?

    Many thanks

  • Sebastian Kruse 0

    Yay, Xamarin.Forms Hot Reload is stable… And it does not even survive 30 seconds of testing. Do you test such features only with newly created template projects or did you even test any of those features with actual projects? The Xamarin Previewer was the very same mess as soon as some kind of framework like MvvmCross is used which is pretty common to be honest…

    So just another “feature” that is just there to be ignored. Maybe it’s time to change the motto of Microsoft to “Microsoft, it just don’t work at all”. After all the “great” updates over the last couple month to nearly everything owned by Microsoft.

  • Kalixt 0

    AAB, thanks.

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