How to store simple Key-Value data?

To store simple key-value data in a Xamarin.Forms application, you can use the Preferences class provided by Xamarin.Essentials. This class allows you to save and retrieve application preferences in a key/value store, which is supported across multiple platforms including iOS, Android, and UWP.

Steps to Store and Retrieve Key-Value Data

1. Add Xamarin.Essentials to Your Project:
   Ensure that Xamarin.Essentials is added to your project. You can do this via NuGet Package Manager in Visual Studio.

2. Initialize Xamarin.Essentials:
   Initialize Xamarin.Essentials in your MainActivity (for Android) and AppDelegate (for iOS).

   Android:

   csharp Copy

   using Android.App;
   using Android.Content.PM;
   using Android.Runtime;
   using Android.OS;
   using Xamarin.Essentials;
   
   [Activity(Label = "YourApp", MainLauncher = true, ConfigurationChanges = ConfigChanges.ScreenSize | ConfigChanges.Orientation)]
   public class MainActivity : global::Xamarin.Forms.Platform.Android.FormsAppCompatActivity
   {
       protected override void OnCreate(Bundle savedInstanceState)
       {
           base.OnCreate(savedInstanceState);
           Xamarin.Essentials.Platform.Init(this, savedInstanceState);
           global::Xamarin.Forms.Forms.Init(this, savedInstanceState);
           LoadApplication(new App());
       }
   }

   iOS:

   csharp Copy

   using Foundation;
   using UIKit;
   using Xamarin.Essentials;
   
   [Register("AppDelegate")]
   public class AppDelegate : global::Xamarin.Forms.Platform.iOS.FormsApplicationDelegate
   {
       public override bool FinishedLaunching(UIApplication app, NSDictionary options)
       {
           Xamarin.Essentials.Platform.Init(this, options);
           global::Xamarin.Forms.Forms.Init();
           LoadApplication(new App());
           return base.FinishedLaunching(app, options);
       }
   }

3. Store a Value:
   Use the Preferences.Set method to store a value with a specific key.

   csharp Copy

   using Xamarin.Essentials;
   
   // Store a string value
   Preferences.Set("username", "JohnDoe");
   
   // Store an integer value
   Preferences.Set("userAge", 30);

4. Retrieve a Value:
   Use the Preferences.Get method to retrieve the value associated with a specific key.

   csharp Copy

   // Retrieve a string value
   string username = Preferences.Get("username", "default_value");
   
   // Retrieve an integer value
   int userAge = Preferences.Get("userAge", 0);

5. Remove a Value:
   Use the Preferences.Remove method to remove a specific key and its associated value.

   csharp Copy

   Preferences.Remove("username");

6. Clear All Values:
   Use the Preferences.Clear method to clear all stored preferences.

   csharp Copy

   Preferences.Clear();

Example Code

Here is a simple example demonstrating how to store, retrieve, and remove key-value data using Xamarin.Essentials Preferences:

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