What is accuracy of GPS location?

Ans : 

CLLocationAccuracy class provides accuracy constant.

kCLLocationAccuracyKilometer:

Accurate to the nearest kilometer.

kCLLocationAccuracyBestForNavigation:

The highest possible accuracy that uses additional sensor data to facilitate navigation apps. 

kCLLocationAccuracyBest:

The best level of accuracy available.

kCLLocationAccuracyNearestTenMeters:

Accurate to within ten meters of the desired target. 

kCLLocationAccuracyHundredMeters:

Accurate to within one hundred meters.

kCLLocationAccuracyThreeKilometers:

Accurate to the nearest three kilometres.