Chapter 1, Creating the TrackMyWalks Native App, focuses on how to set up a basic cross-platform native app structure using Xamarin.Forms before proceeding with adding new, and updating existing, packages within your solution.

You’ll learn how to create C# classes that will act as the model for our app, and will create content pages that will form the user interface. We will also cover the differences between developing apps using Xamarin Studio and Microsoft Visual Studio.

Chapter 2, MVVM and Data Binding, introduces you to the architecture behind the MVVM pattern, and how you can implement this within your application by adding new Views and the associated Models.

You’ll learn how to create the underlying C# class files that will act as the ViewModels for your app, and update existing content pages to data-bind with the ViewModels to represent the information that will be displayed within the user interface for our application.

Chapter 3, Navigating within the MVVM Model - The Xamarin.Forms Way, builds upon your working knowledge of the MVVM design pattern architecture to show you how you can navigate through the ViewModels by creating a C# class that acts as the navigation service for our app, and updates our existing WalkBaseViewModel class to include additional abstract class methods each of our ViewModels will inherit; in turn, you'll update content pages to bind with the ViewModels to allow navigation between these Views to happen.

Chapter 4, Adding Location-Based Features within Your App, focuses on how you can incorporate platform-specific features within the TrackMyWalks app, which is dependent on the mobile platform, by creating a location service C# class that will include several class methods for both the iOS and Android platforms.

You’ll learn how to properly perform location updates whether the application's state is in the foreground or background by registering the app as a background-necessary application.

Chapter 5, Customizing the User Interface, shows you how you can work with DataTemplates to lay out your views neatly within your applications user interface by creating a C# class. You’ll get accustomed to working with platform-specific APIs to extend the default behavior of Xamarin.Forms controls using custom renderers to create a custom picker, before moving on to learn how to use the Xamarin.Forms Effects API to customize the appearance and styling of native control elements for each platform by implementing a CustomRenderer class.

Finally, you will learn how to manipulate the visual appearance of data bound using value and image converters.

Chapter 6, Working with Razor Templates, introduces you to the Razor HTML templating engine, and how you can use it to create a hybrid mobile solution. You'll learn how to build a book library mobile solution using the power of Razor templates, how to create and use models within your application, and how to connect this up to a SQLite database to store, retrieve, update, and delete book details.

Chapter 7, Incorporating API Data Access using Microsoft Azure App Services, shows you how you can use Microsoft Azure App services to create your very first live, cloud-based backend HTTP web service to handle all the communication between the cloud and the app. You’ll learn how to create a DataService API that will allow the app to consume the API so that it can retrieve, store, and delete walk trail information from the cloud, all from within the TrackMyWalks app.

Chapter 8, Making our App Social – Using the Facebook API, shows you how you can use both Xamarin.Auth and the Facebook SDK to incorporate social networking features within the TrackMyWalks app to obtain information about a Facebook user, as well as post information to their Facebook wall.

You’ll learn how to create a sign-in page that allows users to log in to your app using their Facebook credentials, and how to create a FacebookApiUser class that will be used to store information about the logged-in user, and use the Open Graph API to retrieve certain information about the user.

Finally, you will see how you can leverage the Facebook library to post walk data to your Facebook profile page, so you can show off your Walk Trail progress to your friends and/or work colleagues.

Chapter 9, Unit Testing your Xamarin.Forms App using the NUnit and UITest Frameworks, focuses on showing you how to create and run unit tests using the NUnit and UITest testing frameworks right within the Xamarin Studio IDE. You'll learn how to write unit tests for our ViewModels that will essentially test the business logic to validate that everything is working correctly before testing the user interface's portion using automated UI testing.

Chapter 10, Packaging and Deploying your Xamarin.Forms Applications, focuses on how to submit your TrackMyWalks iOS app to the Apple App Store, and share your creations with the rest of the community. You'll learn the steps required to set up your iOS development team, as well as certificates for both development and distribution, and you will learn how to create the necessary provisioning profiles for both your development and distribution builds and create the necessary app IDs for your application.

Finally, you will learn how to register your iOS devices so that your users can download and test your apps on their iOS devices and learn how to prepare your TrackMyWalks iOS app for submission to iTunes Connect using the Xamarin Studio IDE.

The minimum requirement for this book is an Intel-based Macintosh computer running OS X El Capitan 10.11. We will be using Xamarin Studio 6.1.2, which is the Integrated Development Environment (IDE) used for creating Xamarin.Forms applications using C#, as well as Xcode 8.2.1 to compile our iOS app and run this within the simulator.

Almost all the projects that you create with the help of this book will work and run on the iOS simulator. However, some projects will require an iOS or Android device to work correctly. You can download the latest versions of Xamarin Studio and Xcode at:

Xamarin Studio: http://xamarin.com/download

Xcode: https://itunes.apple.com/au/app/xcode/id497799835?mt=12

This book is intended for developers who have a working experience of application development principles, as well as a basic knowledge of Xamarin and C# coding and wish to expand their knowledge and develop applications using Xamarin.Forms. It is assumed that you are familiar with Object-Oriented Programming (OOP), and have some experience developing C# applications using Xamarin Studio.

In this book, you will find a number of text styles that distinguish between different kinds of information. Here are some examples of these styles and an explanation of their meaning.

Code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles are shown as follows: "One thing you will notice is that our solution contains a file called TrackMyWalks.cs which is part of the TrackMyWalks Portable Class Library."

A block of code is set as follows:

    //
    //  WalkEntryViewModel.cs
    //  TrackMyWalks ViewModels
    // 
    //  Created by Steven F. Daniel on 22/08/2016.
    //  Copyright © 2016 GENIESOFT STUDIOS. All rights reserved.
    //  using TrackMyWalks.Models;
        using TrackMyWalks.ViewModels;
        using Xamarin.Forms;
        namespace TrackMyWalks
       {
           public class WalkEntryViewModel : WalkBaseViewModel
           {

When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:

    //
    //  WalksPage.cs
    //  TrackMyWalks
    //
    //  Created by Steven F. Daniel on 04/08/2016.
    //  Copyright © 2016 GENIESOFT STUDIOS. All rights reserved.
    //
    using System.Collections.Generic;
    using Xamarin.Forms;
    using TrackMyWalks.Models;
    using TrackMyWalks.ViewModels;
    namespace TrackMyWalks
    {
        public class WalksPage : ContentPage
        {
            public WalksPage()
            {

Any command-line input or output is written as follows:

    Last login: Sun Nov 6 10:48:41 on console
    GENIESOFT-MAC-Mini:~ stevendaniel$ curl
    https://trackmywalks.azurewebsites.net/tables/walkentries 
    --header "ZUMO-API-VERSION:2.0.0"

New terms and important words are shown in bold. Words that you see on the screen, for example, in menus or dialog boxes, appear in the text like this: "if you click on the Proceed With ... button, it will navigate to the walks Trail Details page where you can begin your trail, by clicking on the Begin this Trail button."

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