The Xamarin platform consists of a number of elements that allow you to develop applications for iOS and Android:

• Mono .NET framework – Provides a cross-platform implementation of the extensive features in Microsoft’s .NET framework.
• C# language – Allows you to use a familiar syntax and wide features like Generics, LINQ and the Parallel Task Library most used for Mobile Developement.
• Compiler – Depending on the platform, produces a native app (eg. iOS) or an integrated .NET application and runtime (eg. Android).
• IDE tools – The Visual Studio on Mac and Windows allows you to create, build, and deploy Xamarin projects.

Xamarin Architecture

Common Mobile Software Patterns

Patterns are an established way to capture recurring solutions to common problems, there are few key patterns that are useful to understand in building maintainable mobile applications.

Model, View, ViewModel (MVVM) – The Model, View , ViewModel pattern is popular with frameworks that support data-binding, such as Xamarin Forms. It was popularized by XAML -enabled SDKs like Windows Presentation Foundation(WPF), where ViewModel acts as a go-between the data (Model) and user interface (View) via data binding and commands.

Model, View, Controller (MVC) –  MVC is most often used when building User Interfaces and provides for a separation between the actual definition of a UI Screen (View), the engine behind it that handles interaction (Controller), and the data that populates it (Model). The model is actually a completely optional piece and therefore, the core of understanding this pattern lies in the View and Controller. MVC is a popular approach for iOS applications.

Singleton – The Singleton pattern provides for a way in which only a single instance of a particular object can ever exist.

Each of the patterns will be examined in more detail as their practical use is illustrated in the case studies. Wikipedia has more detailed descriptions of the MVVM, MVC, Facade, Singleton, Strategy and Provider patterns (and of Design Patternsgenerally).

Recently, I have implemented few applications using Xmarin 7.0 and upload on google play console. please download to your android devices.

URL to install apps : Google Play Store URL