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);