CODEWITHSUNDEEP
c#androidxamarinxamarin.formsauto-update
Lê Gia Lễ
Lê Gia Lễ

Reputation: 540

Correct way to implement auto-update for Android app built with Xamarin.Forms

I recently started building my mobile application using cross-platform Xamarin.Forms toolkit and I'm having a hard time trying to implement some sort of an auto-update mechanism for it.

More particularly, my app has some XML files along with images stored in assets folder, all packed up in the apk file, published to the Google Play.

What I want is to edit and update those xml and assets without publishing a new version of apk in the play store. But I also know that once packed into an apk, these resources cannot be changed unless the user manually downloads and updates the app via the store.

So I currently use the following work around:

  1. I put all of the stuff like XML files or images that I want to update on my server then make an API for specifying their version as well as providing downloadable items.
  2. Inside my app, I have a value representing the current version of the assets. Whenever the app starts, a background process will call the server's API and check if this version value matches the one on the server.
  3. If the versions to not match, the service will automatically download the stuff from the server and store inside user device's internal storage.
  4. Then the app will replace local resources with the resources from the server.

The problem is that this work-around of mine is too clumsy and hard to implement. Any ideas that can help me with a cleaner or more proper solution?

Upvotes: 3

Views: 5645

Answers (1)

SushiHangover
SushiHangover

Reputation: 74134

Your logic is correct... if you are "versioning" assets outside of the APK, you need to track a "version" of the local assets vs. the server|remote-based assets and download/cache new assets when the remote assets are newer...

You could use APK expansion (*.obb) files to bundle your "assets" separate from your .apk bundle. But anytime you need to change an .obb (even if it is a patch-based .obb) the application version has to change and thus you have to upload an .apk with a new version to the store even if nothing else in it has changed.

re: APK Expansion Files

The new .aab format (the .apk replacement) allows you to modify individual components of the application and thus the user get a true delta of the differences of what they have installed vs. the new changes resulting in very small update sizes. Again like an .obb, the app's version needs to change and thus a new .aab has to be uploaded.

Note: Xamarin does not currently support direct building of .aab bundles (like Android Studio does), but they can be "handmade" from the MSBuild artifacts.

re: Android App Bundles

Personally for scenarios like yours, I just use a single versioned .zip that includes all the files that can dynamically change between application level version|releases and thus only track that single file (unzipping into local app cache upon download). An version file (or just a file-hash) on the server contains the latest version and URL of the zip file and the zip file itself contains a matching version file. No cached files, download and unzip the file. Upon app update check, compare the version file in the cache to the server version and download/unzip if needed. (Note: I do not even use a separate "semantic version", I just use the SH1 hash of the zip file).

Upvotes: 4

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