Background sync lets you upload and download data automatically to and from your mobile app. Your data stays up to date and you don't need to interact manually with the app.
Background sync works for each project. You can use it for new projects in the cloud and for projects you already downloaded. If you work on more than one project, turn on background sync for each project.
The following conditions must be met for background sync to work:
If you do not open a project for 30 days, background sync turns off automatically.
For new projects you have not downloaded, you can turn on background sync when you select the project to download.
For projects you already downloaded to your iOS device:
From the Projects list, tap the More menu
for a project.
Tap Edit download options.
Turn on the Background sync toggle.
Tap Apply changes.