Category

Xamarin.Forms

I ran into an issue where my Xamarin.Forms UWP app, which uses MvvmCross and SyncFusion SfCharts stopped showing charts once I created the app package for the Windows Store (i.e. created *.appxupload package with .NET native tool chain).

I went hunting for a fix and rather quickly found a post on the SyncFusion official support forum about that problem. I also found that there’s a official Knowledge Base article:

Post: https://www.syncfusion.com/forums/127258/chart-not-rendered-in-uwp-release-mode

Knowledge Base: https://www.syncfusion.com/kb/7149/how-to-make-syncfusion-xamarin-forms-chart-to-work-in-uwp-in-release-mode-when-net-native-tool-chain

Both saying the same thing, that one should go to their App.xaml.cs file and add an extra assembly (i.e. typeof(Syncfusion.SfChart.XForms.UWP.SfChartRenderer).GetTypeInfo().Assembly)
to their Xamarin.Forms.Init() parameter in the OnLaunched() method. Basically add this code:

Unfortunately, this doesn’t work with MvvmCross 6.1.2 (probably doesn’t work with 6.2.0 as well – haven’t checked though). The charts are still not showing, even though the SfCharts assembly got included.

I can’t be 100% sure of the reason behind this problem but I suspect it’s because of the fact, that MvvmCross framework is now handling the Xamarin.Forms initialization for you. Because of that the Xamarin.Forms.Init() method is called multiple times – once in the App.xaml.cs and once inside of the framework. Another assumption, based on the results we’re seeing, is that Xamarin.Forms.Init() works in a way that the last in is the one that gets served – meaning that if the App.xaml.cs call happens before the MvvmCross one, then the SfChart assembly is not going to be included and Native tool chain compilation will strip it out.

A bit more explanation on this: Mvx framework calls the Xamarin.Forms.Init() method inside of the base Setup file – MvxFormsWindowsSetup calling Xamarin.Forms.Init(). The remedy is simple, move the code from App.xaml.cs to the GetViewAssemblies() override in your Setup.cs file. The GetViewAssemblies() method is being called at the launch of the app by MvvmCross and it is designed to retrieve additional assemblies to pass as a parameter into the Xamarin.Forms.Init() method – which is exactly what we want.

That’s it – you should see your charts again!

 

I’ve stumbled upon this issue straight after I released my app into the store…

I did a brief search on the Internet what could be causing such behaviour and majority of posts were pointing at some issues with cached data by Google Play Store and/or Google Play Services somehow breaking installation process. They were suggesting cleaning cache of these to solve the problem. Combination of clearing cached data, uninstalling the app, restarting the device and even ejecting the SD card did not help

I didn’t give up though. I was fortunate enough to have a device at home, that I was able to reproduce this with. At least it showing some errors when trying to deploy and debug the app using Visual Studio – which was a good start. Each and every time I tried to deploy the app onto the device I was getting the error

ADB0010: Unexpected install output: Failure [INSTALL_PARSE_FAILED_MANIFEST_MALFORMED: Failed parse during installPackageLI: /data/app/vmdl1021324914.tmp/base.apk (at Binary XML file line #28): <service> does not have valid android:name]

It didn’t tell me much, so I started googling it. Some of the StackOverflow posts (#1, #2) that I found were pointing me at the problem with package name capital letters. Yep, I did put some capital letters in my app name (i.e. com.progrunning.AirQuality, which ultimately became com.progrunning.airquality). I changed the name of the app in the AndroidManifest.xml but I was still getting that error…I had no choice but to check what’s actually being generated/added by Xamarin.Forms into the AndroidManifest.xml when packaging the app. I went to my bin\Debug folder, to try to unzip the generated *.apk file – *.apk is just fancy *.zip file. Unfortunately, at this stage the AndroidManifest.xml file in the *.apk is nothing but binary data. Which looks something like this when opened with Visual Studio Code:

Fortunately, thanks to this StackOverflow answer, there’s a way of reading what’s in the *.apk package. I located the aapt.exe file, where my android sdk got installed (in my case it was C:\Programming\SDK\Android\android-sdk\build-tools\27.0.3) and ran the command

aapt.exe l -a “C:\Programming\Projects\Own\AirQuality\AirQuality\AirQuality.Android\bin\Debug\com.progrunning.airquality.apk”

The above prints out quite a bit of stuff (you can probably narrow it with some pipes and grep commands – I’m no expert on these though), but we’re interested only in the AndroidManifest.xml file. From the error that I got when trying to deploy and debug the app I knew that something that prevents this from happening is located at the line 28. I finally got my answer:

I used capital letters for my background service (biggggggggggggg mistake!):

Changing it to lowercase fixed the issue

 

EDIT: The problem didn’t seem to be happening for the Android versions 8.0+. It was only affecting 6.0 and 7.0 (maybe more but these two versions are definitely confirmed)

EDIT2: I ended up with my app name having capital letters in it – that was not the problem