iPhone/iPad: Limiting Mobile Data Usage
To reduce the mobile data activity an iPhone/iPad:
- Settings → iTunes & App Store → Use Mobile Data → Off.
- Settings → Mobile → untick every app you don't want to use mobile data.
- Settings → Personal Hotspot → Personal Hotspot → Off.
- Settings → Safari → Reading List / Use Mobile Data → Off.
You can also enable Low Power Mode when away from wifi services. This causes the device to significantly reduce background activity so apps won't be communicating over the Internet as much.