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Xamarin 4.x Cross-Platform Application Development - Third Edition

By : Peppers

Xamarin 4.x Cross-Platform Application Development

By: Peppers

Overview of this book

Xamarin is a leading cross-platform application development tool used by top companies such as Coca-Cola, Honeywell, and Alaska Airlines to build apps. Version 4 features significant updates to the platform including the release of Xamarin.Forms 2.0 and improvements have been made to the iOS and Android designers. Xamarin was acquired by Microsoft so it is now a part of the Visual Studio family. This book will show you how to build applications for iOS, Android, and Windows. You will be walked through the process of creating an application that comes complete with a back-end web service and native features such as GPS location, camera, push notifications, and other core features. Additionally, you’ll learn how to use external libraries with Xamarin and Xamarin.Forms to create user interfaces. This book also provides instructions for Visual Studio and Windows. This edition has been updated with new screenshots and detailed steps to provide you with a holistic overview of the new features in Xamarin 4.

Preface

Preface

What this book covers

What you need for this book

Who this book is for

Conventions

Reader feedback

Customer support

Free Chapter

1. Xamarin Setup

1. Xamarin Setup

Understanding Xamarin

Installing Xcode

Installing Xamarin on Mac OS X

Setting up the Android emulator

Installing Xamarin on Windows

Connecting Visual Studio to a Mac for iOS development

Enrolling in the iOS developer program

Registering as a Google Play developer

Summary

2. Hello, Platforms!

2. Hello, Platforms!

Building your first iOS application

Understanding Apple's MVC pattern

Using the iOS designer

Building your first Android application

Understanding Android activities

Xamarin's Android designer

Summary

3. Code Sharing Between iOS and Android

3. Code Sharing Between iOS and Android

Learning the MVVM design pattern

Comparing project organization strategies

Setting up a shared project

Working with portable class libraries

Using preprocessor statements

Simplifying dependency injection

Implementing Inversion of Control

Summary

4. XamSnap - A Cross-Platform App

4. XamSnap - A Cross-Platform App

Starting our sample application concept

Developing our model layer

Writing a mock web service

Writing the ViewModel layer

Writing unit tests

Summary

5. XamSnap for iOS

5. XamSnap for iOS

Understanding the basics of an iOS app

Xamarin.iOS Build Options

Using UINavigationController

Implementing the login screen

Using segues for navigation

Setting up UITableView

Adding a friends list screen

Adding a list of messages

Composing messages

Summary

6. XamSnap for Android

6. XamSnap for Android

Introducing the Android Manifest

Setting up Material Design

Adding a login screen

Using ListView and BaseAdapter

Implementing the friends list

Composing messages

Summary

7. Deploying and Testing on Devices

7. Deploying and Testing on Devices

iOS provisioning

Android device settings

Understanding the linker

Understanding AOT compilation

Avoiding common memory pitfalls

Summary

8. Contacts, Camera, and Location

8. Contacts, Camera, and Location

Introducing Xamarin.Mobile

Accessing contacts

Looking up GPS location

Accessing the photo library and camera

Summary

9. Web Services with Push Notifications

9. Web Services with Push Notifications

Learning Windows Azure

Exploring Azure Functions

Using the Apple Push Notification service

Implementing Google Cloud Messaging

Summary

10. Third-Party Libraries

10. Third-Party Libraries

The Xamarin Component Store

Porting existing C# libraries

Objective-C bindings

Java bindings

Using XPath in Java bindings

Summary

11. Xamarin.Forms

11. Xamarin.Forms

Creating Hello World in Xamarin.Forms

Understanding the architecture behind Xamarin.Forms

Using XAML in Xamarin.Forms

Using data-binding and MVVM

Summary

12. App Store Submission

12. App Store Submission

Following the iOS App Store Review Guidelines

Submitting an app to the iOS App Store

Signing your Android applications

Submitting the app to Google Play

Tips for building a successful mobile app

Summary

Accessing the photo library and camera

The last major feature of Xamarin.Mobile is the ability to access photos in order to give users the ability to add their own content to your applications. Using a class called MediaPicker, you can pull photos from the device's camera or photo library and optionally display your own UI for the operation.

Let's modify MessageViewModel to support photos. First, add the following property:

public string Image { get; set; }

Next, we need to modify the following lines in the SendMessage method:

if (string.IsNullOrEmpty(Text) && string.IsNullOrEmpty(Image))
   throw new Exception("Message is blank.");
 
//Then further down 
var message = await service.SendMessage(new Message
{
     UserName = settings.User.Name,
     Conversation = Conversation.Id,
     Text = Text,
     Image = Image,
     Location = location,
});
//Clear our variables 
Text =
      Image = null;

Next, we will need to modify the UI layer to prompt for photos....

CONTINUE READING

83

Tech Concepts

36

Programming languages

73

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