Resource synchronization or SYNC is a an option that allows you instantly update live applications without uploading a new binary on the Store. This is convenient if you have lots of files to update and you do not have time to wait for a new binary approval.
To benefit from this option you need to enable SYNC before you request the binary to upload on the Store. On the last step of submission process enable(if not) SYNC to use this option within the application.
Note: SYNC option is enabled by default for app.xml
Publish the application on iTunes Connect, Google Play Store or Amazon Store. Once the application is approved you can use Resource Synchronization to update the existing files(images, sounds, HTML files, etc.).
You can show or hidden SYNC option from App Settings -> In-App Settings option.
To choose what files do you want to sync, go to app’s Dashboard -> Edit Pages -> Resource Manages. The check-box on the far right of the appeared table represents the sync feature state of the file (page).
Note: Just files set as SYNC in Resource Manager will be updated.