Iphone 3g just got ios 4, now locations not working

Question

I am trying to use location services in maps for example and since i got ios 4 today, it tells me cannot determine your location. I have reset the network settings,then location settings,then reset all settings and still nothing. Everything else works great but this location feature wont work now.
Any ideas?

Answer 1

There are two different "problems" here:
1. a more fine grained permissions framework where enabled restrictions or disabled location services prevets the use of location services in one, more or all applications.
To fix this problem: disable restrictions, allow location services for all or specific apps.
2. WiFi based location services in iOS 4 functions differently from earlier versions, giving a lower positioning accuracy. This results in location services giving less accurate readings in some locations, while other locations - that was OK before the upgrade, and works with SkyHooks site - rendering no positioning possible.
Other results of the new algorithm is that when used in locations with many access points the position of the device keeps jumping around and that the positioning works longer when moving out of the range of the access point used by the device to connect to the Internet.
As an example of the second problem I have the following readings:
Location A: WiFi connection to access point, access point and all neighboring access points are registred at SkyHook, all neighboring access points are out of range.
3.1.3: The exact location of the access point as registered at SkyHook ± 150 m.
4.0: 50 m away on the middle of the road ± 250 m.
Location B: WiFi connection to access point, access point and all neighboring access points are registred at SkyHook, one neighboring access points is also in range.
3.1.3: Appox 5m from device location ± 250 m.
4.0: Approx 10m from device location ± 80 m.
Location C: WiFi connection to access point, access point and a number of neighboring access points are registred at SkyHook, some neighboring access points in range.
3.1.3: Appox 0-50 m from device location ± 150 m.
4.0: Center of registered access points in range ± 150 m.
Location D: device moved out of range of access point, access point and a number of neighboring access points are registred at SkyHook, some neighboring access points in range.
3.1.3: Appox 0-50 m from device location ± 150 m.
4.0: Center of registered access points in range ± 250 m.
Location E: WiFi connection to access point, access point and a number of neighboring access points are registred at SkyHook, all neighboring access points are out of range.
3.1.3: The exact location of the access point as registered at SkyHook ± 150 m.
4.0: No position fix possible.
Location F: Device moved from location E until another access point registered at SkyHook comes into range:
3.1.3: The exact location of the access point as registered at SkyHook ± 150 m.
4.0: Center of registered access points in neighborhood ± 250 m.
Location G: WiFi connection to an SSID provided by a number of access points in neighborhood using several different changing channels. Some access points registered at SkyHook, others not.
3.1.3: The exact location of the access point connected to as registered at SkyHook ± 150 m.
4.0: Center of registered access points in range ± 150 m. When channels change the algorithm get confused and the location starts jumping around resulting in the location ending up up to 500 m from device ± 250 m.
Apart from moving, there does not appear to be a fix for the second problem. You have to wait for Apple or the location service provider(s) to fix the problem - note: this may take some time - or we could be lucky within the near future.
The old algorithm appear to be more focused on the access point connected to, while the new algorithm apparently focuses more on the neighborhood. It appears to ignore signal strength, and the possibility that all other access points in the neighborhood may be out of range (in this case because the access point in question had been optimised for maximum bandwidth and minimal interference).
Conclusion: the new algorithm apparently only works in areas with many SkyHook registrations if the device is moved out of range of the access point is was connected to, or if the ranges of neighboring access points overlap.