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Tag: Dependency Service

Adding a SQLite database to Xamarin.Forms

SQLite Logo
Source: Wikipedia (https://en.wikipedia.org/wiki/SQLite)

SQLite is an excellent choice for local storage within a mobile application. It is lightweight and with virtually zero configuration. Adding SQLite to a Xamarin.Forms project is fairly straightforward:

1. Add the nuget package SQLite-net PCL to each project (PCL, Android, & iOS)
Author = Frank A Krueger
ID = sqlite-net-pcl

2. Add an interface to the PCL project called: ISQLiteService.cs

3. Add a class to the iOS project called: SQLiteService.cs

4. Add a class to the Android project also called SQLiteService.cs

5. Add a class to the PCL project called: BaseItem.cs

6. Add a class to the PCL project called: Database.cs

7. To create a table model, simply create a class with public properties (with getters and setters) of the types and names of each field in the table. The class should inherit from BaseItem; this adds an auto incrementing ID field.

8. Create an instance of Database.cs called: database
To create a table simply call database.CreateTable();

Xamarin.Forms SQLiteExample ScreenshotYou now have a fully functioning database in Forms. To see a database in action, checkout out my example project on GitHub.

 

If you have any comments, questions, or suggestions, feel free to leave a comment below.

Using Dependency Services with Xamarin.Forms

When developing with Xamarin.Forms, you will quickly find yourself in a situation where some of the native platforms’ functionalities were not implemented in the Forms API. In these situations, you can use the power of a Dependency Service to access the native Xamarin for each platform.

For example, say you want to access the devices’ GPS functionality. Each platform has GPS capabilities, yet function slightly differently. In a situation like this, using a dependency service will provide you access to all the native functionality on each platform within the shared code of the portable class library (PCL).

A dependency service is exactly what it sounds like. Within the PCL project, you will have a service (interface) that abstracts the functionality that you need access to in each platform. Within each platform project, you will create the native implementation that correlates with your shared abstraction.

Let’s go ahead and implement a simple dependency service. Forms does not provide access to your application’s cookie storage. While the cookie storage is handled automatically for WebViews and other network requests, you may need to access the cookies directly.

1. Within the PCL project, create an interface file called: INativeCookieService.cs

2. Add the methods and properties you are abstracting

3. Within the Android project, create a class called: NativeCookieService.cs

4. Add the assembly attribute:
[assembly: Dependency(typeof(MyCoolApp.Droid.NativeCookieService))]

5. Have the class implement: INativeCookieService

6. Add the native functionality

7. Repeat steps 3 – 6 for iOS (and Windows if you are supporting Windows). Make sure to use the iOS namespace rather than the Android on step 4

Whenever you need to use the native functionality within the PCL, you simply make the call: