AirDrop, has been a part of Apple’s mobile operating system since iOS 7. It gives you the option to share (and receive) files with other devices that are nearby - whichmay be everybody or just contacts depending on your settings.
The ability to see other devices (or be seen yourself) is in the Share menu. To get to the AirDrop settings, swipe your finger up from the bottom of the screen to open the Control Center panel.
• Tap the AirDrop button in the Control Center. In the default setting, AirDrop makes your device visible to others in the Share menu to “Contacts Only,” meaning just the people listed in your Contacts app.
• However, if you have “Everyone” selected in the settings instead, anybody within range can see your device in their own Share menu and request to send you a file. As one might expect, the opportunity to harass with unwanted images is a temptation some cannot resist - leaving you prone to “cyber flashing”.
• To disable AirDrop — and your phone’s visibility — select “Receiving Off” in the Control Center’s AirDrop settings.
For further security measures, turn off Wi-Fi and Bluetooth (which AirDrop needs to function) in the Control Center when you are not using them, and change the name of your iPhone to something vague and less personal.