Book Image

Mastering Xamarin.Forms - Second Edition

By : Ed Snider
Book Image

Mastering Xamarin.Forms - Second Edition

By: Ed Snider

Overview of this book

Discover how to extend and build upon the components of the Xamarin.Forms toolkit to develop effective, robust mobile app architecture. Starting with an app built with the basics of the Xamarin.Forms toolkit, we'll go step by step through several advanced topics to create a solution architecture rich with the benefits of good design patterns and best practices. We'll start by introducing a core separation between the app's user interface and the app's business logic by applying the MVVM pattern and data-binding. Then we will focus on building out a layer of plugin-like services that handle platform-specific utilities such as navigation and geo-location, as well as how to loosely use these services in the app with inversion of control and dependency injection. Next we'll connect the app to a live web-based API and set up offline synchronization. Then, we'll dive into testing the app logic through unit tests. Finally, we will setup Visual Studio App Center to automate building, testing, distributing and monitoring the app.
Table of Contents (11 chapters)

Adding pull-to-refresh

As with the new entry page, when the main page is loading our data, we should present the user with a loading indicator so that they know their list of entries is on its way. However, since the main page is using a data-bound ListView instead of a static TableView, we can use the ListView pull-to-refresh functionality to indicate when our data is being loaded. Pull-to-refresh also has the benefit of allowing users to easily refresh the screen and load any new data that might be available. Xamarin.Forms makes adding pull-to-refresh very easy, and we will still use the IsBusy property from our BaseViewModel, just as we did on the new entry page.

The Xamarin.Forms ListView pull-to-refresh API requires two things: an ICommand that handles refreshing the bound source of the ListView, and a boolean field that indicates whether the ListView is currently refreshing...