Can I add GPS coordinates to contacts on the iPhone?
It might seem like GPS coordinates can be added to a contact on the iPhone, after all when tapping a pin in the Maps app iOS provides the option. The reality is that Contacts only supports storing addresses, not latitude and longitude coordinates. The location that's actually stored in the Contacts app will not be accurate unless the GPS coordinates can be associated with an address.
This means that if the location is in a rural area or somewhere that doesn't have an address that the Contacts app can identify, it will default to a different place. This could be the center of the closest zip code, town or even further from your original pin location.
Many users would like to tell Siri to remind them when they leave specific places, however if these locations can't be associated with an address, then using Contacts to store these places isn't be possible.