Filter bad CLLocation objects in didUpdateLocations function

We get location objects in CLLocationManager’s

func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation])

The issue however is it also gives us some CLLocation objects which are low quality. Since plotting low-quality CLLocation or using them can lead to a bad user experience. We can solve this by using the following properties of CLLocation object

  • horizontalAccuracy
  • verticalAccuracy
  • timestamp

All the accuracy properties are double values and represent distance in meters from the actual location. So a lower value represents a higher accuracy and a negative value represents an invalid location.

  • Accuracy value is distance in meters from actual location
  • Lower accuracy value means the CLLocation object is closer to actual location
  • Higer value means in accurate location value
  • Negative accuracy value means garbage data

Keeping all these points in mind we can create a simple function to filter out bad eggs from our CLLocation array

func filterBadLocation(_ location: CLLocation) -> Bool{
    let age = -location.timestamp.timeIntervalSinceNow
    // reject if too old adjust value as per need
    if age > 10{.    
        return false
    }

    // reject if invalid
    if location.horizontalAccuracy < 0{
        return false
    }

    // reject if too far from actual location / inaccurate
    if location.horizontalAccuracy > 100{
        return false
    }

    // reject if invalid
    if location.verticalAccuracy < 0{
        return false
    }

    // reject if too far from actual location / inaccurate
    if location.verticalAccuracy > 100{
        return false
    }

    return true

}

So basically you are not accepting all you get in delegate method but you are filtering what fits your quality criteria.

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