In this chapter, we updated our TrackMyWalks application to allow us to use Facebook to sign in to our app. You learned how you can use both the Xamarin.Auth and the Facebook SDK to authenticate whether the user is a valid Facebook user. Next, you learned how to create a custom FacebookApiUser model and a FacebookCredentials class that are used to store the user's credentials, so that these can be used throughout our app to obtain information about the user.

As we progressed throughout the chapter, you created a Facebook Sign In content page and a custom page renderer class that will allow the user to sign in to the TrackMyWalks app using their Facebook credentials, and updated the ViewModel and content pages so that they can utilize the Facebook functionality appropriately. You learned how to take advantage of the Facebook SDK and post walk data to your Facebook profile page, so you can show off your progress to your friends and/or work colleagues.

In the next chapter, you'll learn how to create and run unit tests within the Xamarin Studio IDE, using the UITest framework, before moving on to learn how to profile our application using the Xamarin Profiler, and how to use the Xamarin Inspector to inspect and debug our user interfaces visually, and fix UI-related problems.