Hows does Significant Location Change work?

Question

Can anyone confirm how Significant Location Change works?

---

1. movement is calculated when the iPhones cell receiver swaps from one cell tower to another as the user moves around?

2. movement is calculated by triangulating between "visible" cell towers to best calculate the users position?

3. movement is calculated by triangulation between "visible" cell towers based on the settings associated with desiredAccuracy?

Answer 1

Don't rely on it working in a specific way. If the way it works isn't documented, you should be open to changes in that respect.

Answer 2

Number 1 is the right answer. This is the reason, those updates come not very often.