Xamarin Cheatsheet¶
Xamarin - Cross-Platform Mobile Apps with .NET
Xamarin ist eine Open-Source-Plattform zum Erstellen moderner und leistungsfähiger Anwendungen für iOS, Android und Windows mit .NET. Xamarin ist eine Abstraktionsschicht, die die Kommunikation von gemeinsam genutztem Code mit zugrunde liegender Plattform-Code verwaltet.
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# Install Visual Studio (Windows) or Visual Studio for Mac (macOS)
# Make sure to include the "Mobile development with .NET" workload
# For iOS development on Windows, you need a Mac with Xcode and Visual Studio for Mac installed
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```bash
# Open Visual Studio Installer
# Check if "Mobile development with .NET" is installed
# Check for Android SDK and NDK
# Visual Studio > Tools > Options > Xamarin > Android Settings
# Check for Xcode and Apple SDKs (macOS)
# Visual Studio for Mac > Preferences > Projects > SDK Locations > Apple
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```bash
# In Visual Studio
# File > New > Project
# Select "Mobile App (Xamarin.Forms)"
# Choose a template (Blank, Tabbed, Shell)
# In Visual Studio for Mac
# File > New Solution
# Select "Multiplatform > App > Xamarin.Forms"
# Choose a template (Blank, Tabbed, Shell)
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```bash
# Select a startup project (Android or iOS)
# Choose a device or emulator
# Click the "Run" button or press F5
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// ContentPage
public class MyContentPage : ContentPage
{
public MyContentPage()
{
Content = new StackLayout
{
Children = { new Label { Text = "Welcome to Xamarin.Forms!" } }
};
}
}
// TabbedPage
public class MyTabbedPage : TabbedPage
{
public MyTabbedPage()
{
Children.Add(new MyContentPage { Title = "Tab 1" });
Children.Add(new MyContentPage { Title = "Tab 2" });
}
}
// FlyoutPage (Master-Detail)
public class MyFlyoutPage : FlyoutPage
{
public MyFlyoutPage()
{
Flyout = new ContentPage { Title = "Menu" };
Detail = new NavigationPage(new MyContentPage());
}
}
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```csharp
// StackLayout
new StackLayout
{
Orientation = StackOrientation.Vertical,
Spacing = 10,
Children = { new Label(), new Button() }
};
// Grid
new Grid
{
RowDefinitions = { new RowDefinition { Height = GridLength.Auto } },
ColumnDefinitions = { new ColumnDefinition { Width = new GridLength(1, GridUnitType.Star) } },
Children = { { new Label(), 0, 0 } }
};
// FlexLayout
new FlexLayout
{
Direction = FlexDirection.Row,
JustifyContent = FlexJustify.SpaceBetween,
Children = { new Label(), new Button() }
};
// AbsoluteLayout
new AbsoluteLayout
{
Children = { { new BoxView { Color = Colors.Blue }, new Rectangle(0, 0, 100, 100) } }
};
// RelativeLayout
new RelativeLayout
{
Children = { { new BoxView(), Constraint.Constant(0) } }
};
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```csharp
// Label
new Label { Text = "Hello, Xamarin!", FontSize = 24 };
// Button
new Button { Text = "Click Me", Command = new Command(() => DisplayAlert("Title", "Message", "OK")) };
// Entry
new Entry { Placeholder = "Enter text" };
// Editor
new Editor { Placeholder = "Enter multi-line text" };
// SearchBar
new SearchBar { Placeholder = "Search..." };
// Slider
new Slider { Minimum = 0, Maximum = 100 };
// Stepper
new Stepper { Minimum = 0, Maximum = 10 };
// Switch
new Switch { IsToggled = true };
// DatePicker
new DatePicker();
// TimePicker
new TimePicker();
// ListView
new ListView
{
ItemsSource = new[] { "Item 1", "Item 2" },
ItemTemplate = new DataTemplate(() =>
{
var cell = new TextCell();
cell.SetBinding(TextCell.TextProperty, ".");
return cell;
})
};
// CollectionView
new CollectionView
{
ItemsSource = new[] { "Item 1", "Item 2" }
};
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```csharp
// MainActivity.cs
[Activity(Label = "@string/app_name", Theme = "@style/AppTheme", MainLauncher = true)]
public class MainActivity : AppCompatActivity
{
protected override void OnCreate(Bundle savedInstanceState)
{
base.OnCreate(savedInstanceState);
SetContentView(Resource.Layout.activity_main);
var button = FindViewById<Button>(Resource.Id.myButton);
button.Click += (sender, e) =>
{
Toast.MakeText(this, "Button Clicked!", ToastLength.Short).Show();
};
}
}
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```csharp
// ViewController.cs
public partial class ViewController : UIViewController
{
public ViewController(IntPtr handle) : base(handle) { }
public override void ViewDidLoad()
{
base.ViewDidLoad();
var button = new UIButton(UIButtonType.System);
button.Frame = new CGRect(20, 200, 280, 44);
button.SetTitle("Click Me", UIControlState.Normal);
button.TouchUpInside += (sender, e) =>
{
var alert = UIAlertController.Create("Title", "Message", UIAlertControllerStyle.Alert);
alert.AddAction(UIAlertAction.Create("OK", UIAlertActionStyle.Default, null));
PresentViewController(alert, true, null);
};
View.AddSubview(button);
}
}
```(This section was empty in the original text, so no translation is needed)
```xml
<!-- MainPage.xaml -->
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
x:Class="MyApp.MainPage">
<StackLayout>
<Label Text="Welcome to Xamarin.Forms!"
VerticalOptions="CenterAndExpand"
HorizontalOptions="CenterAndExpand" />
<Button Text="Click Me" Clicked="OnButtonClicked" />
</StackLayout>
</ContentPage>
```csharp // MainPage.xaml.cs public partial class MainPage : ContentPage { public MainPage() { InitializeComponent(); }
private void OnButtonClicked(object sender, EventArgs e)
{
DisplayAlert("Title", "Message", "OK");
}
}
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public class MyViewModel : INotifyPropertyChanged { private string _name; public string Name { get => _name; set { _name = value; OnPropertyChanged(); } }
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
}
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// Push a new page
await Navigation.PushAsync(new DetailsPage());
// Pop a page await Navigation.PopAsync();
// Pop to root await Navigation.PopToRootAsync();
// Pass data await Navigation.PushAsync(new DetailsPage(item));
// Modal navigation
await Navigation.PushModalAsync(new ModalPage());
await Navigation.PopModalAsync();
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// Define an interface in shared code
public interface ITextToSpeech
{
void Speak(string text);
}
// Implement the interface in platform-specific projects // Android [assembly: Dependency(typeof(TextToSpeech_Android))] namespace MyApp.Droid { public class TextToSpeech_Android : ITextToSpeech { ... } }
// iOS [assembly: Dependency(typeof(TextToSpeech_iOS))] namespace MyApp.iOS { public class TextToSpeech_iOS : ITextToSpeech { ... } }
// Use the service in shared code
DependencyService.Get(This section was empty in the original text, so no translation is needed)csharp
// Create a custom control in shared code
public class MyEntry : Entry { }
// Create a custom renderer in platform-specific projects
// Android
[assembly: ExportRenderer(typeof(MyEntry), typeof(MyEntryRenderer))]
namespace MyApp.Droid
{
public class MyEntryRenderer : EntryRenderer
{
protected override void OnElementChanged(ElementChangedEventArgs
// iOS
[assembly: ExportRenderer(typeof(MyEntry), typeof(MyEntryRenderer))]
namespace MyApp.iOS
{
public class MyEntryRenderer : EntryRenderer
{
protected override void OnElementChanged(ElementChangedEventArgs(This section was empty in the original text, so no translation is needed)csharp
// Create an effect in shared code
public class FocusEffect : RoutingEffect
{
public FocusEffect() : base("MyApp.FocusEffect") { }
}
// Implement the effect in platform-specific projects // Android [assembly: ResolutionGroupName("MyApp")] [assembly: ExportEffect(typeof(FocusEffect_Android), "FocusEffect")] namespace MyApp.Droid { public class FocusEffect_Android : PlatformEffect { ... } }
// Use the effect in XAML
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// Subscribe to a message
MessagingCenter.Subscribe
// Send a message MessagingCenter.Send(this, "Hi", "John");
// Unsubscribe
MessagingCenter.Unsubscribe(This section was empty in the original text, so no translation is needed)csharp
// Set a value
Preferences.Set("my_key", "my_value");
// Get a value
var value = Preferences.Get("my_key", "default_value");
### Dateisystemcsharp
// Get the local app data folder
var path = Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData);
var filename = Path.Combine(path, "myfile.txt");
// Write to a file File.WriteAllText(filename, "Hello, Xamarin!");
// Read from a file
var content = File.ReadAllText(filename);
### SQLitecsharp
// Install sqlite-net-pcl NuGet package
// Create a model public class MyItem { [PrimaryKey, AutoIncrement] public int ID { get; set; } public string Text { get; set; } }
// Create a database connection
var db = new SQLiteAsyncConnection(dbPath);
await db.CreateTableAsync
// Save an item await db.InsertAsync(item);
// Get all items
var items = await db.Table## Netzwerkcsharp
var client = new HttpClient();
var response = await client.GetAsync("https://api.example.com/items");
if (response.IsSuccessStatusCode)
{
var content = await response.Content.ReadAsStringAsync();
var items = JsonConvert.DeserializeObject### HttpClientcsharp
// Install Refit NuGet package
// Define an interface
public interface IMyApi
{
[Get("/items")]
Task
// Use the interface
var api = RestService.For### Refitcsharp
// Use a testing framework like NUnit or xUnit
[Test]
public void MyViewModel_MyCommand_ShouldDoSomething()
{
// Arrange
var viewModel = new MyViewModel();
// Act
viewModel.MyCommand.Execute(null);
// Assert
Assert.IsTrue(viewModel.MyProperty);
}
## Testingcsharp
// Use Xamarin.UITest
[Test]
public void AppLaunches()
{
app.Screenshot("First screen.");
}
[Test]
public void TappingButton_ShouldNavigateToDetails()
{
app.Tap(c => c.Button("MyButton"));
app.WaitForElement(c => c.Marked("DetailsPage"));
app.Screenshot("Details screen.");
}
### Komponententestsbash
Build the app in Release mode¶
Archive the app¶
Distribute the archive (e.g., to Google Play)¶
### UI-Testsbash
Build the app in Release mode¶
Archive the app¶
Distribute the archive (e.g., to the App Store)¶
```## Bereitstellung