The Core Location video from WWDC 2014 talks about how IOS 8 uses WiFi access points, RF parametric data, and motion sensor to determine indoor positioning. I have been looking through the current documentation for Core Location and cannot find any detailed information regarding what was brought up in that video.
I go to a university with a closed campus, and wifi is everywhere. If iPhone indeed uses WiFi access points ... to determine indoor positioning, theoretically there should be plenty of signals for the phone to pick up and have a good assessment of indoor positioning. However, I have been testing the accuracy and the performance has been poor.
I would walk down a 200m long building, get the coordinates at both ends, then calculate the distance between them using CLLocation1.distance(from: CLLocation2). The result comes out to be around 5 meters. Also, the .floor instance property never displays what floor I am on. It always displays nil. Was I supposed to tell the phone to check for that property?
TL;DR how does the iPhone check for indoor positioning? Any documentation on it? Can I at least find out which room I am in?
There are some requirements for a facility to use Apple’s Indoor Positioning:
- Be accessible to the general public;
- Have annual visitors in excess of 1 million;
- Have complete reference maps available;
- Have enabled Wi-Fi throughout a venue;
- Have an associated app authorized by the facility owner.
Even in case when all these requirements are met, that custom map will not appear in Apple Maps. But Apple Maps will show a user’s indoor position (blue dot) inside the Apple Maps app, but without noting the floor you’re on or displaying custom map.
Also, there are some important details:
Position Accuracy: 5-10 meters. Basically, Apple can tell if you are in front of a store, but wouldn’t be able to tell you which door you are standing near;
Location Calculation: Apple derives position through its core location APIs, and all calculations are done on device. It uses available GPS signal, Wi-Fi signal and facility physical “texture” (walls, for example) or RF Parametric data to determine the location of a device. It also leverages some of the motion sensors in a device’s M7 chip. More “texture” and stronger Wi-Fi lead to more location accuracy;
Total Addressable Market: Everyone with iOS 8, iPhone 4S or greater and iPad 2 and newer. iPhone 5 or better is recommended.
