In a large shopping mall, a hospital or a building, have you ever had an experience where you could not find a place to go? In this case, the use of traditional positioning method is somewhat inadequate. First of all these places can not use GPS, and WiFi and cellular mobile phone base station positioning error is relatively large. In this case, positioning is called "micro-positioning" technology.
A more important concept in micro-positioning technology-geo-fencing. Geo-fencing is a new application of lbs, which is to surround a virtual geographic boundary with a virtual fence. The phone can receive automatic notifications and warnings when the phone enters, leaves a specific geographic area, or is active in the area. With geo-fencing technology, the location of social networking site owners can help users to register automatically when they enter an area.
Reference: "Best Practices for iOS sensor application development"
"Reading notes" ios-micro-positioning technology