Most of you might never get into the position where app size limits matter to you. Apps should be small and do one thing well and one thing only. But for games or other heavy ressource apps, you might hit those limits. Since Xamarin already addes some extra weight to your app, you might hit those limits sooner than with native development.

Know your limits

For Google Play Store the size limit is pretty low: at only 100MB you’re done while Apple allows you 4GB app size in the store. This is pretty generous, but users per default have a size limit of 100MB for download via cellular which you should keep in mind.

How to reduce your app size

There are different approaches to this topic for the oses, already well described on the pages of apple and google:

Android

https://developer.android.com/topic/performance/reduce-apk-size

iOS

https://developer.apple.com/documentation/xcode/reducing_your_app_s_size

Cannot reduce size - what now?

Well if you for the love of it cannot cut down on app size, there are ways to get around that.

Load resources from a backend

This works for all platforms. You can just download your resources when your app starts the first time, or lazy whenever you need them.

Android App Bundles

Android App Bundles is the new way of trimming down your app. It is powered by the play store, knowing your users device and locale and therefore creating an apk specifically to its needs. Images are only downloaded for your devices’s resolution and language files only for your language. Using App bundles also gives you the added benefit that your app can now have up to 150 MB. https://developer.android.com/topic/performance/reduce-apk-size#app_bundle

Android expansion files

Android expansion files allow to put some more resources like images in one or two more artifacts. Those will either downloaded right away from the playstore or upon first start of your app. You will have to implement your own downloader for that though. https://stackoverflow.com/questions/12371302/android-apk-size-limitation-in-google-play https://developer.android.com/google/play/expansion-files