Introduction

Foreword

As an UWP developer, I am used to using the MVVM pattern to develop my APPs. But when I started to learn Xamarin, I felt a little inconvenience because I have to use the native UI and add a lot of boring event handlers to the controls. I compared several MVVM frameworks and found that MvvmCross might be a good choice to use the MVVM pattern for Xamarin APPs.

MvvmCross is a cross-platform MVVM framework which supports Xamarin, iOS, Xamarin.Android, Xamarin.Mac, Xamarin.Forms, UWP and WPF. It implements the Dependecy Injection pattern, also provide us with various plugins, such as Messenger, Network, File, ResourceLoader and Location, etc, to support different target platforms. We can easily deliver a Xamarin App with it. But as the same as the other MVVM framework, the users need to have a fundamental understanding of MVVM. If not, do not worry. I will show you some basic points regarding the MVVM pattern, and guide you to create your first Xamarin App with MvvmCross.

Just note that MvvmCross updates quickly so you might need to fine-adjust the codes in this article. The current version of MvvmCross is V6.2.1.

The first question is that which type of the shared project you should use. In the .NET world, there are several different ways that we share the codes across different platforms, such as Shared Project, Portable Class Library, and .NET Standard. I highly recommend using the latest .NET Standard library as the Core project, rather than the PCL library. Why? One reason is that you cannot create a new PCL project by VS 2017. And the .NET Standard Library is a formal specification of .NET APIs, so we will have a greater uniformity. According to the docs, it is the next generation of PCL. That is why I think the .NET Standard library is the better one. But there is still a small problem. If you select .NET Standard 2.0 for the Core project, it will not support the old version of Windows 10. It only supports version 10.0.16299 and higher version of Windows 10. Another issue is that some third libraries might not update to support .NET Standard. So, choose the right approach according to your real scenario.

Although MvvmCross provides quite a few templates (some of them are contributed by the third-party developers), it is necessary to understand how to build a new App from zero. So we do not use any third-party templates. I am going to demonstrate how to use MvvmCross to show these features:

  • Data-Binding

  • Lifecycle of the ViewModel

  • Navigation

  • Command

  • ……

It is very boring to introduce a lot of knowledge before you write the first line of code. I will start it directly, then come back to understand the meaning of the codes. Some basic sample codes come from the official documentation of MvvmCross.

You can check the source code of this demo on my GitHub: https://github.com/yanxiaodi/MvvmCrossDemo.

Let's get started!

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