When creating and deploying applications on your device, by default, Xamarin will delete all existing data / application caching. This is not always ideal as it dumps your data as if it were fresh.
To save the data, you need to update the parameter:
In Xamarin Studio, select "Tools"> "Options"> "Projects"> "Android ...". Check "Save data / cache between application deployments"
In Visual Studio, select "Tools"> "Options"> "Xamarin"> "Android Settings" ... Check "Save data / cache between application deployments"
After that, all the general settings or data files created in the local folder of the application will remain.
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