You can use Check In on iPhone to automatically notify a friend that your iPhone has arrived, and choose what details they can see if you don’t successfully complete your Check In. Similarly, if a friend sends you a Check In but their iPhone hasn’t arrived as expected, you can view their location, battery percentage, cellular signal, and more.
Send a Check In
Create or select an existing conversation
Tap the plus (+) > More > Check In > Edit
Choose one of the following
When I Arrive: Specify your destination, how you’re traveling (driving, transit, or walking), and add extra time if needed. When you arrive at your destination successfully, the Check In automatically completes and notifies your friend that your iPhone has arrived.
After a Timer: Specify a period of time—for example, if you’re meeting someone new. If you don’t end the Check In before the time you set, Check In notifies your friend.
After you've selected one of the two options above, tap the blue send button.