.NET MAUI: Implementing Light and Dark Modes

In modern application development, providing users with the ability to switch between light and dark modes has become an essential feature. This functionality not only enhances user experience but also accommodates personal preferences and improves accessibility. In this blog post, we will explore how to implement light and dark modes in .NET MAUI apps using the UserAppTheme property in the App.xaml.cs file.

Understanding the App.xaml.cs File

The App.xaml.cs file in a .NET MAUI application is responsible for defining the application’s startup and initialization logic. It acts as the entry point for the application and provides a central location to handle events and configure application-wide settings.

Setting the UserAppTheme Property

To enable light and dark modes in your .NET MAUI app, you need to access the UserAppTheme property available in the Application.Current object. This property allows you to specify the desired theme for your application.

If your application does not allow the users to change the light/dark modes, but you want to force the app to be in a specified state, you can use the App.xaml.cs constructor, and you can set the UserAppTheme property to either AppTheme.Light or AppTheme.Dark, depending on a predefined default.

Here’s an example of how to set the AppTheme to Light mode:

Application.Current.UserAppTheme = AppTheme.Light;

Similarly, you can set the AppTheme to Dark mode:

Application.Current.UserAppTheme = AppTheme.Dark;
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.NET MAUI: Save any type of object in Preferences

.NET MAUI currently have limitations of the supported types in preferences. They can only store simple data types such as strings, integers, and booleans, and do not support more complex data types such as lists or objects. This can make it difficult to store and retrieve more complex data structures.

How to store arrays and lists, or complex classes in Preferences?

The answer is currently to serialize it. Since Preferences is supporting string saving option, you can serialize your arrays and custom classes, and store the string value.

But be aware to store large amounts of data in Preferences as a string. Consider choosing SQLite to store data when there are more than 50-100 items in an array, or your class is more complex than having 25 properties. As Microsoft marks this as a limitation: Performance may be impacted if you store large amounts of text, as the API was designed to store small amounts of text.

But there are cases when it makes sense to store other types

There are cases when it is easier to store a whole complex object on disk than to store all its properties one by one by calling preferences Set. In this case you may find useful the banditoth.MAUI.PreferencesExtension.

Usage

This package is extending the basic functions of the built in MAUI Essentials IPreferences by letting the developers to save any type of object. This is done by using JSON serialization, and saving the raw jsons as strings with the default IPreferences implementation. Since JSON arrays can be serialized back to any collection type, you can use different types when Setting the value and when Getting it back.

There are several ways to access this extension.

Dependency Injection

    private readonly IPreferences preferences;

    public MainPage(IPreferences preferences)
    {
        InitializeComponent();
        this.preferences = preferences;
    }

    private void Foo()
    {
        List<string> taleItems = new List<string>()
        {
            "The quick brown fox",
            "Jumps over the lazy dog"
        };

        preferences.SetObject<List<string>>("Tale", taleItems);

        string[] taleItemsFromPreferences = preferences.GetObject<string[]>("Tale", null);
    }

Access through Preferences

If you are used to access the preferences trough the static class, you can use this tool by accessing the Default property on the Preferences class. You can call the SetObject or GetObject extension method on it.

            // Setting the value
            Preferences.Default.SetObject<IDeviceInfo>("Device_Information", DeviceInfo.Current);
            // Getting the value
            Preferences.Default.GetObject<IDeviceInfo>("Device_Information", null);

Package’s own static reference

You can also access the SetObject or GetObject method on PreferencesExtension static class.

            // Setting the value
            PreferencesExtension.SetObject<DisplayOrientation>("Last_Display_Orientation", orientation);
            // Getting the value
            PreferencesExtension.GetObject<DisplayOrientation>("Last_Display_Orientation", DisplayOrientation.Landscape);
This content has 1 year. Some of the information in this post may be out of date or no longer work. Please, read this page keeping its age in your mind.

.NET MAUI: Get unique device and installation ids for your app

Why unique device and installations identifiers are important?

First, let’s define what we mean by a unique device and installation identifiers. Essentially, these are codes that are assigned to individual devices and installations of an app. They allow developers to track usage on a specific device and identify individual installations of the app. This is important because it allows us to understand how users are interacting with our app and identify patterns in usage. For example, if we notice that a particular device is experiencing a high number of crashes, we can use the device ids to track down the specific device and troubleshoot the issue.

Another important use case for unique device and installation identifiers is providing targeted and personalized content or experiences for users. For example, we can use this information to show users personalized advertisements or to offer them special deals or promotions based on their usage patterns.

In addition to these benefits, device and install ids also play an important role in security and fraud prevention. By tracking the usage of our app on specific devices, we can identify and prevent unauthorized access to the app or service. This can help to protect user data and prevent fraud and other malicious activities.

How to get unique identifiers in .NET MAUI?

On Android, you can get a unique device id from the os with accessing Secure.AndroidId.
On iOS, UIDevice.CurrentDevice.IdentifierForVendor is the solution. It requires platform specific knowledge to access the provider APIs. I’ve extended my banditoth.MAUI.Packages library, so you do not need to worry about having this knowledge, just use the banditoth.MAUI.DeviceId NuGet package.

Once you have installed banditoth.MAUI.DeviceId, you need to initalize  the plugin within your MauiProgram.cs‘s CreateMauiApp method. Use the .ConfigureDeviceIdProvider extension method with the using banditoth.MAUI.DeviceId;

    public static MauiApp CreateMauiApp()
    {
        var builder = MauiApp.CreateBuilder();
        builder
            .UseMauiApp<App>()
            .ConfigureFonts(fonts =>
            {
                fonts.AddFont("OpenSans-Regular.ttf", "OpenSansRegular");
                fonts.AddFont("OpenSans-Semibold.ttf", "OpenSansSemibold");
            })
            .ConfigureDeviceIdProvider();
#if DEBUG
        builder.Logging.AddDebug();
#endif

        return builder.Build();
    }

Use the code with by resolving an instance of IDeviceIdProvider.

The GetDeviceId method returns an unique device identifier. On Android it serves the data from AndroidId, on iOS and MacCatalyst it uses the IdentifierForVendor. Windows returns the GetSystemIdForPublisher().Idas a string.

The GetInstallationId method generates an unique identifier for the application, which will be stored until the application is being reinstalled, or the application’s data being erased.

This content has 1 year. Some of the information in this post may be out of date or no longer work. Please, read this page keeping its age in your mind.

.NET Error: “The current NET SDK does not support targeting NET 7.0.”

The current NET SDK does not support targeting NET 7.0. Either target . NET 6.0 or lower, or use a version of the NET SDK that supports .NET 7.0.

This error message is indicating that the version of the .NET SDK that you are currently using does not support targeting .NET 7.0. In order to resolve this error, you have three options:

  • Update your Visual Studio instance to the latest available.
  • Target .NET 6.0 or lower in your application by modifying the target framework in your project file (e.g. .csproj) to a version lower than 7.0, and then rebuild your application.
  • Use a version of the .NET SDK that supports .NET 7.0. You can check the version of the SDK you are currently using by running dotnet --version in a command prompt or terminal, and then update it to the latest version that supports .NET 7.0.
    • You can check the SDK version by running dotnet –list-sdks and you can update your SDK version by running dotnet update sdk
    • Once you have updated your SDK version, you should be able to build your application targeting .NET 7.0 without encountering this error.
This content has 1 year. Some of the information in this post may be out of date or no longer work. Please, read this page keeping its age in your mind.

.NET MAUI Jailbreak and root detection

banditoth.MAUI packages just got a new package: banditoth.MAUI.JailbreakDetector. 2022 was a great year for me in a software development perspective, my MAUI packages got downloaded over more than 1500 times, which is a great achievement for me. I’m keeping up the work, and having a new package on my palette: A lightweight root and jailbreak detection algorithm for Android and iOS with .NET MAUI.

What is jailbreaking?

Jailbreaking is the process of removing the limitations imposed on iOS devices by Apple. It allows users to install apps and tweaks that are not available on the App Store, customise the appearance of the operating system, and access features that are otherwise restricted. Jailbreaking an iOS device is considered to be a violation of Apple’s terms of service, and it can also make the device more vulnerable to security risks.

What is rooting?

Rooting is the process of allowing users of smartphones, tablets and other devices running the Android mobile operating system to attain privileged control (known as root access) over various Android subsystems. Rooting is often performed with the goal of removing limitations that hardware manufacturers or carriers place on some devices, thereby providing the latest versions of Android to devices that no longer receive official updates, or unlocking features which are otherwise unavailable to the user. Rooting is also often used to remove pre-installed apps, known as bloatware, that the manufacturer or carrier included on the device and which the user may not have wanted.

Why jailbreak and root protection is important?

When a device is jailbroken or rooted, it can become more vulnerable to security risks because the jailbreak process involves disabling certain security measures and exposing the device to potentially malicious software. This can compromise the security and stability of the operating system, and it can also make the device more susceptible to being hacked or compromised in other ways. By implementing jailbreak protection, software developers can help to ensure that their apps and systems are running on a secure and stable platform, which can help to protect the device and its users from various types of attacks and vulnerabilities.

Use jailbreak and root protection in .NET MAUI

Install the banditoth.MAUI.JailbreakDetector NuGet in order to protect your apps against vulnerabilities.

Initalize the library in the MauiApp.cs file within the CreateMauiApp method, like this:

public static MauiApp CreateMauiApp()
		{
			var builder = MauiApp.CreateBuilder()
				.UseMauiApp<App>()
				...
				.ConfigureJailbreakProtection(configuration =>
				{
					configuration.MaximumPossibilityPercentage = 20;
					configuration.MaximumWarningCount = 1;
					configuration.CanThrowException = true;
				});
			return builder.Build();
		}

You can dependency inject the jailbreak detector instance, by resolving an instance of IJailbreakDetector. Store the instance in a private readonly field in your class, or use it directly.

    public async Task CheckJailbreakOrRoot()
    {
        if(_jbDetector.IsSupported())
        {
            if(await _jbDetector.IsRootedOrJailbrokenAsync())
            {
                // Code when jailbroken or rooted
            }
            else
            {
                // Code when clear
            }
        }
    }

By calling ScanExploitsAsync you can process the discovered exploits and warnings during the scan – It returns a ScanResultScanResult has a property named PossibilityPercentage. This percentage tells you how confidently you can tell whether a device has been jailbroken or rooted. Different types of tests contribute different weights to the final result.

    public async Task CheckJailbreakOrRoot()
    {
        ScanResult scan = await _jbDetector.ScanExploitsAsync();
        
        if(scan == null)
            return;
            
        foreach(var exploit in scan.Exploits)
        {
            // Get detailed information about the exploits here
        }
        
        if(scan.PossibilityPercentage < 5)
        {
            // Custom code when only 5% possible that the device is rooted or jailbroken
        }
    }

Remarks

Please note that there are many different kinds of jailbreaks and roots. It is possible that this package does not properly support the detection of these different techniques. If you find that filtering does not work on your device, please help by expanding the code repository.

This content has 1 year. Some of the information in this post may be out of date or no longer work. Please, read this page keeping its age in your mind.