Practical .NET MAUI Tips and Code Snippets

Get the Android platform instance.

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#if ANDROID
    var activity = Microsoft.Maui.ApplicationModel.Platform.CurrentActivity;
#endif

Get the Android platform context.

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var context = Android.App.Application.Context;
// or
context = Platform.AppContext;

Check the Android build version.

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if (Android.OS.Build.VERSION.SdkInt >= Android.OS.BuildVersionCodes.R)
{
}

When setting parameters for cross-platform scenarios, ensure parameters for all platforms are set to avoid warnings.

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<!-- No warning -->
<Setter Property="FontSize" Value="{OnPlatform Android=16,WinUI=15}"/> 
<!-- Warning -->
<Setter Property="FontSize" Value="{OnPlatform Android=16}"/> 

Releasing in APK format on Android may cause issues; switch back to AAB format.
If the project references third-party .so files with special characters or irregular casing in their names, it may cause the released app to malfunction. Rename the files to be short and standardized.
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For Android build properties in Visual Studio, refer to this link.

Specify the Android target SDK version by modifying the AndroidManifest.xml file.

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<manifest xmlns:android="http://schemas.android.com/apk/res/android">
    <application android:allowBackup="true" android:icon="@mipmap/appicon" android:roundIcon="@mipmap/appicon_round" android:supportsRtl="true" android:noHistory="true"></application>
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
    <uses-permission android:name="android.permission.WRITE_SETTINGS"/>
    <uses-permission android:name="android.permission.WRITE_SECURE_SETTINGS"/>
    <uses-permission android:name="android.permission.READ_SETTINGS"/>
    <uses-permission android:name="android.permission.READ_SECURE_SETTINGS"/>
    <!-- Add target version -->
    <uses-sdk android:targetSdkVersion="29" /> 
</manifest>

Get all settings strings on the Android platform.

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var list = Intent.Class.GetFields();
// ACTION_AIRPLANE_MODE_CHANGED
// ACTION_ALARM_CHANGED
// EXTRA_ALARM_COUNT

Modify Android platform system settings. Refer to settings.

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// Modify the system property persist.sys.language to zh_CN
Settings.System.putString(getContentResolver(), Settings.System.LANGUAGE, "zh_CN");

Reboot or shutdown (requires root permissions).

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Java.Lang.Runtime.GetRuntime().Exec("su");
// Reboot
Java.Lang.Runtime.GetRuntime().Exec("reboot");
// Shutdown
Java.Lang.Runtime.GetRuntime().Exec("reboot -p");

Close the current app.
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Application.Current.Quit();

Request system permissions. For detailed permissions, refer to the official documentation.

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var state = await Permissions.RequestAsync<Permissions.Bluetooth>();
if (state != PermissionStatus.Granted)
{
    if (Application.Current != null && Application.Current.MainPage != null)
    {
        await Application.Current.MainPage.DisplayAlert($"Warning", $"Missing required permissions, the app will not function properly!", $"OK");
    }
}

Forcefully close already running processes.

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Process process = Process.GetCurrentProcess();
var pro = Process.GetProcessesByName(process.ProcessName);
foreach (var p in pro)
{
    if (p.Id != process.Id)
    {
        if (p.MainModule.FileName == process.MainModule.FileName)
        {
            p.Kill();
        }
    }
}

Get the IP address.

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var upAndNotLoopbackNetworkInterfaces = NetworkInterface.GetAllNetworkInterfaces().Where(n => n.NetworkInterfaceType != NetworkInterfaceType.Loopback
                                                                                          && n.OperationalStatus == OperationalStatus.Up);

foreach (var networkInterface in upAndNotLoopbackNetworkInterfaces)
{
    var iPInterfaceProperties = networkInterface.GetIPProperties();

    var unicastIpAddressInformation = iPInterfaceProperties.UnicastAddresses.FirstOrDefault(u => u.Address.AddressFamily == AddressFamily.InterNetwork);
    if (unicastIpAddressInformation != null)
    {
        return unicastIpAddressInformation.Address.ToString();
    }                
}