Re: [android-developers] Re: How to: Free to Paid App and retain preference and db files?

Hi,

I want to ask something about LVL.

From my brief understanding, LVL add additional code to check back with Google Play server and refuse to run if it was not a paid version.

Is there possibility to have the check in Google Play server and not allow user to update if the copy installed is not a purchase version? This way, developer don't have to include LVL code in every app publish. Of course in-app billing is not applicable.

On Sunday, 1 July 2012 15:05:28 UTC+8, Dianne Hackborn wrote:

On Sat, Jun 30, 2012 at 9:17 AM, Mystique wrote:

I was also thinking to write a simple app that generate hash value and write it in a file, user will purchase this app and my main app will look for this file and compare the hash value. Will this work? Does Google allow this?

The are two separate apps, so they run under different uids, so can't generally share files.  You could do hacks with putting the file to a location on external storage where app permissions are not enforced, but a content provider would be the more formally correct way to do this -- it allows you to have security between the two (protecting the provider with a signature-only permission) and guarantee things like no other applications being able to get in the middle and manipulate the data that is transferred.

Definitely don't use shared user IDs just for this.

To be honest, I think this is a great example of where in-app billing work well, instead of needing to have two different versions of an app.  Just be sure to use the kind of billing product that persists with the user's account. :)

--
Dianne Hackborn
Android framework engineer
hackbod@android.com

Note: please don't send private questions to me, as I don't have time to provide private support, and so won't reply to such e-mails.  All such questions should be posted on public forums, where I and others can see and answer them.

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