Don't allow updates of your e-mail, calendar, contacts, Facebook messages, or your OneDrive, Dropbox or iCloud files to be synced in the background.
- Go to Settings in the main menu and select iCloud.
- Move the slider next to Use cellular data to the left to disable this option.
If you don't see this option, you can disable mobile data completely for iCloud (or other apps). For this, return to Settings and choose Cellular. Move the slider next to iCloud to the left to disable this option.
iCloud will now only sync when you are connected to Wi-Fi.
For your e-mail accounts, calendars and contacts:
- Go to Settings in the main menu and select Mail, contacts, calendars.
- Select Fetch new data.
- Move the slider next to Push to the left to disable this option.
- Check each of your accounts and select Manually.