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Développement Mobile

How to Develop Mobile Apps with Xamarin in 2026

18 minINTERMEDIATE
C#MobileXamarin
Lire en français

Introduction

Xamarin allows developing native mobile applications for iOS and Android using C# and .NET. This approach reduces maintenance costs through code sharing. In 2026, Xamarin.Forms remains relevant for intermediate projects requiring a declarative UI. This tutorial guides you step by step to a functional application with navigation and data binding.

Prerequisites

  • Visual Studio 2022 with Xamarin workloads
  • .NET 6+ and Xamarin.Forms 5.x
  • Basic knowledge in C# and XAML
  • Apple developer account and configured Android SDK

Creating the Project

terminal
dotnet new Xamarin.Forms -n MonAppMobile
cd MonAppMobile
dotnet restore

This command initializes a Xamarin.Forms cross-platform project with the Shared, Android and iOS folders. The restore downloads essential NuGet dependencies like Xamarin.Essentials.

App.xaml Configuration

App.xaml
<?xml version="1.0" encoding="utf-8" ?>
<Application xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             x:Class="MonAppMobile.App">
    <Application.Resources>
        <ResourceDictionary>
            <Style TargetType="Button">
                <Setter Property="BackgroundColor" Value="#2196F3" />
            </Style>
        </ResourceDictionary>
    </Application.Resources>
</Application>

App.xaml defines global resources. The style applied to buttons ensures visual consistency across all platforms without code duplication.

Main Page in XAML

MainPage.xaml
<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             x:Class="MonAppMobile.MainPage">
    <StackLayout Padding="20">
        <Entry x:Name="NomEntry" Placeholder="Your name" />
        <Button Text="Submit" Clicked="OnValiderClicked" />
        <Label x:Name="ResultLabel" FontSize="20" />
    </StackLayout>
</ContentPage>

This XAML file creates a simple interface with an input field and button. The names allow referencing from code-behind for event binding.

Page C# Logic

MainPage.xaml.cs
using Xamarin.Forms;
namespace MonAppMobile
{
    public partial class MainPage : ContentPage
    {
        public MainPage()
        {
            InitializeComponent();
        }

        private void OnValiderClicked(object sender, EventArgs e)
        {
            string nom = NomEntry.Text;
            ResultLabel.Text = $"Hello {nom}!";
        }
    }
}

The code-behind handles the button event and updates the label. This XAML/C# separation facilitates maintenance and unit testing.

Data Model

Models/Utilisateur.cs
namespace MonAppMobile.Models
{
    public class Utilisateur
    {
        public string Nom { get; set; }
        public int Age { get; set; }
    }
}

This POCO model will be used for data binding. It follows naming conventions for automatic binding in ListViews.

Binding and ViewModel

ViewModels/MainViewModel.cs
using System.ComponentModel;
using Xamarin.Forms;
namespace MonAppMobile.ViewModels
{
    public class MainViewModel : INotifyPropertyChanged
    {
        private string _nom;
        public string Nom
        {
            get => _nom;
            set { _nom = value; OnPropertyChanged(); }
        }
        public event PropertyChangedEventHandler PropertyChanged;
        protected void OnPropertyChanged([System.Runtime.CompilerServices.CallerMemberName] string propertyName = null)
            => PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }
}

The ViewModel implements INotifyPropertyChanged for reactive binding. This allows the UI to update automatically without manual code.

Best Practices

  • Use MVVM to separate business logic from the UI
  • Manage permissions with Xamarin.Essentials
  • Test on Android emulators and iOS simulators
  • Optimize images with FFImageLoading
  • Regularly update NuGet packages

Common Errors

  • Forgetting InitializeComponent() in the constructor
  • Not implementing INotifyPropertyChanged correctly
  • Ignoring rendering differences between iOS and Android
  • Using blocking calls on the UI thread

Going Further

Deepen your Xamarin knowledge with our advanced modules on Shell navigation and REST API integration. Discover our Learni trainings.