Start by adding a reference to Microsoft.Extensions.Logging.Debug. You could do it like this if you only want it in debug mode:
<ItemGroup Condition="'$(Configuration)' == 'Debug'">
<PackageReference Include="Microsoft.Extensions.Logging.Debug" Version="6.0.0" />
</ItemGroup>
Then when the application starts:
var builder = MauiApp.CreateBuilder();
// ...
#if DEBUG
builder.Services.AddLogging(
configure =>
{
configure.AddDebug();
}
);
#endif
You could also add filters:
#if DEBUG
builder.Services.AddLogging(
configure =>
{
configure
.AddDebug()
.AddFilter("MyCompany.MyApp.Namespace", LogLevel.Trace)
.AddFilter("Microsoft", LogLevel.Warning);
}
);
#endif
Android logging (Logcat)
If you want to use the native logging support on Android, an easy fix for this is to add a reference to Microsoft.Extensions.Logging.Console and then configure it:
builder.Services.AddLogging(
configure =>
{
configure.AddDebug();
configure.AddConsole();
}
);
While this works, the logs are a bit hard to read. A better way is to use a custom logging provider that wraps the native logging support. In the Android folder, add this code:
using Microsoft.Extensions.Logging;
namespace MyMauiApp;
public class AndroidLoggerProvider : ILoggerProvider
{
public AndroidLoggerProvider()
{
}
public ILogger CreateLogger(string categoryName)
{
// Category name is often the full class name, like
// MyApp.ViewModel.MyViewModel
// This removes the namespace:
int lastDotPos = categoryName.LastIndexOf('.');
if (lastDotPos > 0)
{
categoryName = categoryName.Substring(lastDotPos + 1);
}
return new AndroidLogger(categoryName);
}
public void Dispose() { }
}
public class AndroidLogger : ILogger
{
private readonly string Category;
public IDisposable BeginScope<TState>(TState state) => null!;
public bool IsEnabled(LogLevel logLevel) => true;
public AndroidLogger(string category)
{
Category = category;
}
public void Log<TState>(LogLevel logLevel, EventId eventId, TState state, Exception? exception, Func<TState, Exception?, string> formatter)
{
string message = formatter(state, exception);
Java.Lang.Throwable? throwable = null;
if (exception is not null)
{
throwable = Java.Lang.Throwable.FromException(exception);
}
switch (logLevel)
{
case LogLevel.Trace:
Android.Util.Log.Verbose(Category, throwable, message);
break;
case LogLevel.Debug:
Android.Util.Log.Debug(Category, throwable, message);
break;
case LogLevel.Information:
Android.Util.Log.Info(Category, throwable, message);
break;
case LogLevel.Warning:
Android.Util.Log.Warn(Category, throwable, message);
break;
case LogLevel.Error:
Android.Util.Log.Error(Category, throwable, message);
break;
case LogLevel.Critical:
Android.Util.Log.Wtf(Category, throwable, message);
break;
}
}
}
And then you configure it like this:
builder.Services.AddLogging(
configure =>
{
// You don't need the debug logger on Android if you use AndroidLoggerProvider.
// configure.AddDebug();
#if ANDROID
#if DEBUG
LogLevel androidLogLevel = LogLevel.Debug;
#else
LogLevel androidLogLevel = LogLevel.Information;
#endif
configure
.AddProvider(new AndroidLoggerProvider())
.AddFilter("MyMauiApp", androidLogLevel);
#endif
}
);
