AppCenter Extensions for Xamarin.Forms

For the past 3 years or so I have been AppCenter for Crash Reporting and Analytics in Xamarin based apps. During this time, I have mostly built enterprise focused apps using Xamarin.Forms and as a developer I always think about code reuse which usually comes in the form of a library. Early this year, I decided to create and open source a set of convenience classes and extension methods to simplify Crash Reporting and Analytics using AppCenter and called it AppCenterExtensions.

The core features of the project are the following:

  • Simplified user interaction reporting using ICommand implementations
  • Automatic page tracking in Xamarin.Forms including time spent on screen
  • Extension methods for crash reporting
  • Anonymous user information configuration

This library is distributed as 2 NuGet packages

Getting Started

This library is configured almost the same way as the AppCenter SDK. You provide the AppCenter secrets, and specify whether to anonymize the user information. Both Crash Reporting and Analytics are always enabled when using AppCenterSetup.

AppCenterSetup.Instance.Start(
    "[iOS AppCenter secret]",
    "[Android AppCenter secret]",
    anonymizeAppCenterUser: true);

or

await AppCenterSetup.Instance.StartAsync(
    "[iOS AppCenter secret]",
    "[Android AppCenter secret]",
    anonymizeAppCenterUser: true);

The reason for the async API here is because anonymizeAppCenterUser internally relies on an async API. The synchronous API’s for starting AppCenter are non-blocking methods that do a fire-and-forget call to StartAsync(string,bool).

Anonymous User Information
The component AppCenterSetup exposes a method called UseAnonymousUserIdAsync() which sets the UserId in AppCenter to the first 8 characters a GUID that is unique per app installation. This can be used as a support key for uniquely identifying application users for instrumentation and troubleshooting. The support key can be attached to all HTTP calls by using the DiagnosticDelegatingHandler

AppCenter Crash Report

Error Reporting
The library exposes extension methods to the Exception class for conveniently reporting Exceptions to AppCenter

try
{
    // Something that blows up
    explosives.Detonate();
}
catch (Exception e)
{
    // Safely handle error then report
    e.Report();
}

HTTP Error Logging
The library provides a HttpMessageHandler implementation that logs non-successfuly HTTP results to AppCenter Analytics. This component will also attach HTTP headers describing the AppCenter SDK Version, Install ID, and a support key to all HTTP requests. The logged failed responses will contain the Endpoint URL (including the HTTP verb), Response status code, how the duration of the HTTP call. This will be logged under the event name HTTP Error

You will in most (if not all) cases would want to keep a singleton instance of the HttpClient. The DiagnosticDelegatingHandler is designed with unit testing in mind and accepts an IAnalytics and IAppCenterSetup interface, it also accepts an inner HttpMessageHandler if you wish to chain multiple delegating handlers.

var httpClient = new HttpClient(new DiagnosticDelegatingHandler());
await httpClient.GetAsync("https://entbpr4b9bdpo.x.pipedream.net/");

In the example above we made an HTTP GET call to the RequestBin endpoint https://entbpr4b9bdpo.x.pipedream.net. This will result in the following we inspected in RequestBin

AppCenter Crash Report
ITrackingCommand

This library provides 3 convenience implementations of ICommand that will report the action to AppCenter Analytics after successfully invoking the execute callback method

  • TrackingCommand - This implementation accepts an Action as the Execute callback and a Func<bool> as the CanExecute callback
  • TrackingCommand - This implementation accepts an Action<T> as the Execute callback and a Func<T, bool> as the CanExecute callback
  • AsyncTrackingCommand - This implementation accepts a Func<Task> as the execute callback and a Func<bool> as the CanExecute callback. This also exposes a CompletionTask property that the consumer can await if desired. The Execute(object parameter) method here is a non-blocking call
using System.Threading.Tasks;
using System.Windows.Input;
using ChristianHelle.DeveloperTools.AppCenterExtensions.Commands;
using ChristianHelle.DeveloperTools.AppCenterExtensions.Extensions;
using Microsoft.AppCenter.Crashes;
using Xamarin.Essentials;

namespace SampleApp.ViewModels
{
    public class AboutViewModel : BaseViewModel
    {
        public AboutViewModel()
        {
            AsyncButtonTappedCommand = new AsyncTrackingCommand(
                OnAsyncButtonTapped,
                nameof(AsyncButtonTappedCommand).ToTrackingEventName(),
                nameof(AboutViewModel).ToTrackingEventName());

            ButtonOneTappedCommand = new TrackingCommand(
                OnButtonOneTapped,
                nameof(ButtonOneTappedCommand).ToTrackingEventName(),
                nameof(AboutViewModel).ToTrackingEventName());

            ButtonTwoTappedCommand = new TrackingCommand<string>(
                OnButtonTapped,
                nameof(ButtonTwoTappedCommand).ToTrackingEventName(),
                nameof(AboutViewModel).ToTrackingEventName());
        }

        public ICommand AsyncButtonTappedCommand { get; }
        public ICommand ButtonOneTappedCommand { get; }
        public ICommand ButtonTwoTappedCommand { get; }

        private Task OnAsyncButtonTapped()
            => Browser.OpenAsync("https://xamarin.com");

        private void OnButtonOneTapped() { }

        private void OnButtonTwoTapped(string obj) { }
    }
}

Specifying the screenName argument in the constructor is optional and when this is not provided manually then it will use the declaring Type name from the method that instantiated the ITrackingCommand instance and convert it to a more analytics friendly event name using the ToTrackingEventName() extension method. In the example above, if the nameof(AboutViewModel).ToTrackingEventName() parameter is not provided then the owner declaring Type is AboutViewModel and the ScreenName will be set to "About"

Automatic Page Tracking
Automatic page tracking is enabled by replacing the base class of the ContentPage to classes to use TrackingContentPage class. By doing so the library will send page tracking information to AppCenter after leaving every page. Currently, the library will send the page Type, Title, and the duration spent on the screen. The library is rather opinionated on how to log information, and this will only change if I get a request to do so. Duration spent on screen is calculated using a Stopwatch that is started upon Page OnAppearing and is reported to Analytics upon OnDisappearing. The event name is based on the Type name of the Page and is split into multiple words based on pascal case rules and afterwards removes words like Page, View, Model, Async. For example: UserSettingsPage or UserSettingsView becomes User Settings

XAML Example:

<?xml version="1.0" encoding="utf-8"?>
<ext:TrackingContentPage 
    xmlns="http://xamarin.com/schemas/2014/forms" 
    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" 
    xmlns:d="http://xamarin.com/schemas/2014/forms/design" 
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:ext="clr-namespace:AppCenterExtensions.XamarinForms;assembly=AppCenterExtensions.XamarinForms"
    mc:Ignorable="d" 
    x:Class="SampleApp.Views.ItemDetailPage" 
    Title="{Binding Title}">

    <StackLayout Spacing="20" Padding="15">
        <Label Text="Text:" FontSize="Medium" />
        <Label Text="{Binding Item.Text}" d:Text="Item name" FontSize="Small" />
        <Label Text="Description:" FontSize="Medium" />
        <Label Text="{Binding Item.Description}" d:Text="Item description" FontSize="Small" />
    </StackLayout>

</ext:TrackingContentPage>

Custom Trace Listener
This library includes a trace listener implementation that reports to AppCenter. The reason for this is to cater to those who have implemented error handling or reporting using Trace Listeners, these types of users can just swap out (or add on) the AppCenterTraceListener

This implementation implements the following methods:

  • Write(object obj)
  • Write(object obj, string category)
  • WriteLine(object obj)
  • WriteLine(object obj, string category)

If the object provided is an Exception then this is reported to AppCenter Crash Reporting. If the object provided is an instance of AnalyticsEvent then this is sent to AppCenter Analytics

The AnalyticsEvent exposes 2 properties:

  • string EventName { get; } - self explanatory
  • IDictionary<string,string> Properties { get; } - Additional properties to attach to the Analytics event

To set it up you simply add an instance of AppCenterTraceListener to your existing Trace listeners:

Trace.Listeners.Add(new AppCenterTraceListener());

Here’s an example of how to use System.Diagnostics.Trace to report errors

try
{
    // Something that blows up
    explosives.Detonate();
}
catch (Exception e)
{
    // Safely handle error then report
    Trace.Write(e);

    // or
    Trace.Write(e, "Error");

    // or
    Trace.WriteLine(e);

    // or
    Trace.WriteLine(e, "Error");
}

and here’s an example of to use System.Diagnostics.Trace to send analytics data

public partial class App : Application
{
    private const string StateKey = "State";

    public App()
    {
        // Some initialization code ...

        Trace.Listeners.Add(new AppCenterTraceListener());
    }

    protected override void OnStart()
        => Trace.Write(
            new AnalyticsEvent(
                nameof(Application),
                new Dictionary<string, string>
                {
                    { StateKey, nameof(OnStart) }
                }));

    protected override void OnSleep()
        => Trace.Write(
            new AnalyticsEvent(
                nameof(Application),
                new Dictionary<string, string>
                {
                    { StateKey, nameof(OnSleep) }
                }));

    protected override void OnResume()
        => Trace.Write(
            new AnalyticsEvent(
                nameof(Application),
                new Dictionary<string, string>
                {
                    { StateKey, nameof(OnResume) }
                }));
}

Task Extensions
This library includes a few Task extension methods with AppCenter error reporting in mind. Possible exceptions that occur in the async operation are swallowed and reported to AppCenter. These extension methods will internally wrap the Task in a try/catch and await the Task using ConfigureAwait(false).

Here are usage some examples

Fire and Forget on a Task (Note: Forget() returns void)

var task = someClass.SomethingAsync()  
task.Forget()

Awaitable Task (also available for Task<T>)

var task = someClass.SomethingAsync()  
await task.WhenErrorReportAsync();


Generate Android Translations from Google Sheets

In previous articles Generating ResX translations from Google Sheets and Generate iOS InfoPlist.strings Translations from Google Sheets, I wrote about using Google Sheets as a translation tool by using the GOOGLETRANSLATE built in function to generate translation files for a Xamarin based solution. For this post, I will demonstrate something very similar, but instead of ResX files or InfoPlist.strings, I’ll generate strings.xml files for Android. For the sake of this article I created this sample Google Sheets

For a quick recap, we will use a tool called csvtrans written by my colleague and good friend, Ricky Kaare Engelharth. The tool is built with .NET Core and can be installed using this command

dotnet tool install -g csvtrans

Using the tool is also straight forward and it also comes with some quick start instructions

USAGE: csvtrans [--help] [--sheet <document id> <sheet name>]
            [--csv <url or path>] [--format <apple|android|resx>]
            [--outputdir <directory path>] [--name <string>]
            [--convert-placeholders <regex pattern>]

OPTIONS:

    --sheet, -s <document id> <sheet name>
                        specify a Google Sheet as input.
    --csv, -c <url or path>
                        specify a online or local cvs file as input.
    --format, -f <apple|android|resx>
                        specify the output format.
    --outputdir, -o <directory path>
                        specify the output directory.
    --name, -n <string>   specify an optional name for the output.
    --convert-placeholders, -p <regex pattern>
                        convert placeholders to match the output format.
    --help                display this list of options.

Here’s an example usage of tool

csvtrans --sheet 1mrMkhItrIDsPwEKMlR8JJ3Pgj1K6zUv0AhmBT4jWRqs Android --format android --outputdir .\Resources\

The first argument **–-sheet** is the Google Sheet document ID followed by the Sheet Name, the next argument **–-format** specifies the output file format, and the last argument **–-outputdir** specifies the output folder

You can get the Document ID from the URL of the Google Sheet

Here’s an example output

Now I can just bring these files into my project and use them directly. Well, almost! There’s one little problem, and that is that by default the Xamarin.Android csproj tooling explicitly adds each strings.xml file as an AndroidResource. Oddly enough, the csproj format allows to specify wild card folders, so if we want to enable dynamic generation of values/strings.xml translations then we need to manually edit the csproj.

This is actually very easy to do. We just need to replace the lines like

with

This opens up for dynamic translations at build time using your CI/CD build tools of choice


Generate iOS InfoPlist.strings Translations from Google Sheets

In my previous article Generating ResX translations from Google Sheets, I wrote about using Google Sheets as a translation tool by using the GOOGLETRANSLATE built in function to generate translation files for a Xamarin.Forms solution. For this post, I will demonstrate something very similar, but instead of ResX files I’ll generate InfoPlist.strings files in iOS for localizing the permission request prompts for accessing things like Camera, Location, Photo Gallery, etc. For the sake of this article I created this sample Google Sheets

For a quick recap, we will use a tool called csvtrans written by my colleague and good friend, Ricky Kaare Engelharth. The tool is built with .NET Core and can be installed using this command

dotnet tool install -g csvtrans

Using the tool is also straight forward and it also comes with some quick start instructions

USAGE: csvtrans [--help] [--sheet <document id> <sheet name>]
            [--csv <url or path>] [--format <apple|android|resx>]
            [--outputdir <directory path>] [--name <string>]
            [--convert-placeholders <regex pattern>]

OPTIONS:

    --sheet, -s <document id> <sheet name>
                        specify a Google Sheet as input.
    --csv, -c <url or path>
                        specify a online or local cvs file as input.
    --format, -f <apple|android|resx>
                        specify the output format.
    --outputdir, -o <directory path>
                        specify the output directory.
    --name, -n <string>   specify an optional name for the output.
    --convert-placeholders, -p <regex pattern>
                        convert placeholders to match the output format.
    --help                display this list of options.

Here’s an example usage of the tool

csvtrans --sheet 125id155PUq-6Odwg8Nf9fmkgBsKahTGbJYaYBD2rpSg iOS --format apple --outputdir .\Resources --name InfoPlist

The first argument **–-sheet** is the Google Sheet document ID followed by the Sheet Name, the next argument **–-format** specifies the output file format, the argument **–-outputdir** specifies the output folder, and the last argument **--name** specifies the output filename.

You can get the Document ID from the URL of the Google Sheet

Here’s an example output

Now I can just bring these files into my project and use them directly. Well, almost! There’s one little problem, and that is that by default the Xamarin.iOS csproj tooling explicitly adds each InfoPlist.strings file as a BundleResource. Oddly enough, the csproj format allows to specify wild card folders, so if we want to enable dynamic generation of InfoPlist.strings translations then we need to manually edit the csproj.

This is actually very easy to do. We just need to replace the lines like

with

This opens up for dynamic translations at build time using your CI/CD build tools of choice