Adding CLLocationDistances - ios

Question

I'm trying to add CLLocationDistances and getting strange results. Here is my code:
var locations = [CLLocation]()
var totalDistance = CLLocationDistance()
func locationManager(manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
self.locations.append(locations.first!)
if self.locations.count > 1 {
self.calculateTotalDistance()
}
}
func calculateTotalDistance() -> CLLocationDistance {
var y = 0
self.totalDistance = 0
while y < (locations.count - 1) {
let firstLocation = self.locations[y]
let secondLocation = self.locations[y + 1]
let distance = firstLocation.distanceFromLocation(secondLocation)
print(distance)
totalDistance += distance
y++
}
self.updateLabelWithText()
return totalDistance
}
private func updateLabelWithText() {
let distance = String(self.totalDistance)
let message = "Distance in meters: " + distance
self.distanceTextLabel.text = message
}
Essentially, every time I get a new CLLocation object from the system, I append it to my array. Then I iterate through the array, and get the distance between each individual points, and then add them together. I am testing the code on an actual device. As of now, when I run this code, even when I just sit down, the totalDistance variable reaches a count of 100 or so in 10 seconds, despite me not having moved anywhere close to 100 meters.
Also, in the calculateTotalDistance function, I print the distance calculated, and the distances don't seem right at all. Here is an example of what was printed to the console after the app launched for a few seconds:
0.0
1.15645918113224
1.06166528806247
1.06006756503664
1.05847219105153
16.1407724137949
9.67662215264722
0.0
1.15645918113224
1.06166528806247
1.06006756503664
1.05847219105153
16.1407724137949
9.6766221526472
Again, these are values just from when I'm sitting down, so I'm obviously not moving 16 meters, or 9 meters at a time.
Any idea what i'm doing wrong here?
thanks

Answer 1

This is because of accuracy of GPS. Check horizontalAccuracy of CLLocation before adding it to array.
You should also set desiredAccuracy of CLLocationManger to kCLLocationAccuracyBest.