How to make Text Show distance from The user current location to a certain Map annotation

Question

Just wondering How to do that , really would like this in my custom cell in the table view in my app...

Will appreciate any help thank you !

Answer 1

You can calculate the distance between two CLLocation objects with the distanceFromLocation method:

let newYork = CLLocation(latitude: 40.725530, longitude: -73.996738)
let sanFrancisco = CLLocation(latitude: 37.768, longitude: -122.441)
let distanceInMeters = newYork.distanceFromLocation(sanFrancisco)

With an MKMapView object and an MKAnnotationView object, you can calculate the distance between the user's current location and the annotation as follows:

if let userLocation = mapView.userLocation.location, annotation = annotationView.annotation {
  // Calculate the distance from the user to the annotation
  let annotationLocation = CLLocation(latitude: annotation.coordinate.latitude, longitude: annotation.coordinate.longitude)
  let distanceFromUserToAnnotationInMeters = userLocation.distanceFromLocation(annotationLocation)
  ...
}

The following function uses the NSNumberFormatter class to format a distance in meters or kilometres (if the number of meters is more than 1000):

func formatDistance(distanceInMeters: CLLocationDistance) -> String? {
  // Set up a number formatter with two decimal places
  let numberFormatter = NSNumberFormatter()
  numberFormatter.numberStyle = .DecimalStyle
  numberFormatter.maximumFractionDigits = 2

  // Display as kilometers if the distance is more than 1000 meters
  let distanceToFormat: CLLocationDistance = distanceInMeters > 1000 ? distanceInMeters/1000.0 : distanceInMeters
  let units = distanceInMeters > 1000 ? "Km" : "m"

  // Format the distance
  if let formattedDistance = numberFormatter.stringFromNumber(distanceToFormat) {
    return "\(formattedDistance)\(units)"
  } else {
    return nil
  }
}

Putting all this together gives us the following:

if let userLocation = mapView.userLocation.location, annotation = annotationView.annotation {
  // Calculate the distance from the user to the annotation
  let annotationLocation = CLLocation(latitude: annotation.coordinate.latitude, longitude: annotation.coordinate.longitude)
  let distanceFromUserToAnnotationInMeters = userLocation.distanceFromLocation(annotationLocation)
  if let formattedDistance = formatDistance(distanceFromUserToAnnotationInMeters) {
    // Now set the vaue of your label to formattedDistance
  }
}