Book Image

Xamarin Mobile Development for Android Cookbook

By : Matthew Leibowitz
Book Image

Xamarin Mobile Development for Android Cookbook

By: Matthew Leibowitz

Overview of this book

Xamarin is used by developers to write native iOS, Android, and Windows apps with native user interfaces and share code across multiple platforms not just on mobile devices, but on Windows, Mac OS X, and Linux. Developing apps with Xamarin.Android allows you to use and re-use your code and your skills on different platforms, making you more productive in any development. Although it’s not a write-once-run-anywhere framework, Xamarin provides native platform integration and optimizations. There is no middleware; Xamarin.Android talks directly to the system, taking your C# and F# code directly to the low levels. This book will provide you with the necessary knowledge and skills to be part of the mobile development era using C#. Covering a wide range of recipes such as creating a simple application and using device features effectively, it will be your companion to the complete application development cycle. Starting with installing the necessary tools, you will be guided on everything you need to develop an application ready to be deployed. You will learn the best practices for interacting with the device hardware, such as GPS, NFC, and Bluetooth. Furthermore, you will be able to manage multimedia resources such as photos and videos captured with the device camera, and so much more! By the end of this book, you will be able to create Android apps as a result of learning and implementing pro-level practices, techniques, and solutions. This book will ascertain a seamless and successful app building experience.
Table of Contents (20 chapters)
Xamarin Mobile Development for Android Cookbook
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

Optimizing the ListView


In order to make scrolling through out lists as smooth as possible, we need to ensure that the construction and manipulation of the items run as fast and as efficiently as possible.

How to do it...

One way in which we can optimize the list items is to reuse the item view:

  • This is very easy to do, and all we need is to check is whether we can use the convertView parameter before trying to create a new instance of the item:

    if (convertView == null) {
      var inflater = LayoutInflater.From(context);
      convertView = inflater.Inflate(
        Resource.Layout.ListItemLayout, parent, false);
    }
    var firstRow = convertView.FindViewById<TextView>(
      Resource.Id.firstRow);
    firstRow.Text = person.Name;

Another way is to store references to the various subviews so that we don't have look for them each time, as follows:

  1. Create a type that will hold a reference to those subviews:

    private class ViewHolder : Java.Lang.Object {
      public ImageView Icon;
      public TextView FirstRow;
      public...