On Google Play Store
The package name
The app you are going to compile to get the APK must have the same package name as the one which is published.
To find the package name of your published app, go to your Google Play account, and in the list of apps click on the app you want to update.
The package name is just under the name of your app:
Login to your mobimatic dashboard and generate a new apk for your app. (Make sure the package name is the same for the new app.)
Keystore and store password
When you compile an app to create an APK, a keystore certificate is created automatically when you use the APK Generator. This certificate has two associated passwords, one is the Store password, and the other one is Key password. If you want to update an existing app, you will have to get this keystore certificate and the store password.
Since the APK of this previous app has been created from your Mobimatic with the APK Generator, the keystore and the password are stored in your Mobimatic, and in this case you just have to launch the APK generator after having set the package name (if it has changed) and the version, and you obtain an APK to update your app.
Now you get your APK on its new version, just upload it on Google Play to get your app updated (you have to count a few hours before the update is released)
On the App Store
It’s not often the case, but updating in the App Store is much more easier because there is no keystore certificate issues.
The Bundle ID
Like for updating an app on Google Play Store, the app you are going to compile and the app which is already published must have the same bundle ID.
To know the bundle ID of the existing app, just login to https://itunesconnect.apple.com , click on “My Apps”, then click on your app to see its info, and click on the “more” tab, and then on “About this app” to get the bundle ID:
Login to your mobimatic dashboard and generate a new build (if through iOS auto upload – comment that this is a version 2) for your app. (Make sure the bundle ID is the same for the new app.)
Go back to iTunes Connect, and, still in your app sheet, click on “new version”, enter the version number you have set in Mobimatic
Then, you can download the source of your iOS app and go compile it in Xcode.