In recent talk with client, we got an interesting question, if we are able to release new version of application to current users.
We can get certificates for Android Market / App Store, to release application with same signature, but previous supplier is a business enemy, so we want to migrate all users they currently have on the application to our version, via standard update mechanism.
Is this possible? To migrate application to another developer/publisher account and to release an update (which can be completely different, from previous version) so that iTunes/Market update will download and install the new version instead?
I’m looking for solution on both platforms Android Market and Apple App Store, even if it would be necessary to pay some fees and so.
I can only answer for the Android Market:
If you have the release-keys of your old application, you can develop a new application, sign the application with the old key and everybody will be able to upgrade. Of course it will be your job to read the old data, which is saved on the device and transform it to a format which your new app can read, but thats a implementation issue. You will also need access to the google account which was used to upload the application. Google can transfer the account ownership on request.
So: If you got the release-keys, its possible on Android. Otherwise, I’m quite sure that you wont find a solution, you can not upgrade applications if the old and the new version are signed with different keys.