Tap on Add emergency contacts and your iPhone will present your Contacts list to you. Choose whose name you want shown as your emergency contact, and then you are shown their complete contact details. Choose which is the best way to reach them, most typically their cell number. Then iOS asks you who they are and presents a long list of options including spouse, mother, father, and so on. You can add more than one contact. When you're finished choosing them, tap Done. What happens next Hopefully the only thing that ever happens is that the figure you entered for your weight gets progressively less accurate. However, should you be involved in an accident, or any event that incapacitates you, the emergency services can now get this vital detail.