Know nearest pin in a MapView from current location

Question

I am using a MapView with some pins inside a city added. Also, the current user location is displayed in the map. With these two things known (user location and pins) I would like to show in a label the nearest pin from where the user is.

Answer 1

There is no direct API to find that. You have to loop through all annotations.

let pins = mapView.annotations as! [MKAnnotation]
let currentLocation = mapView.userLocation.location!

let nearestPin: MKAnnotation? = pins.reduce((CLLocationDistanceMax, nil)) { (nearest, pin) in
    let coord = pin.coordinate
    let loc = CLLocation(latitude: coord.latitude, longitude: coord.longitude)
    let distance = currentLocation.distanceFromLocation(loc)
    return distance < nearest.0 ? (distance, pin) : nearest
}.1

// Here, `nearestPin` is `nil` iff there is no annotations on the map.

If you don't know the reduce method, see the docs.

Answer 2

Use distanceFromLocation to calculate all the distance:

let distance = fromLocation.distanceFromLocation(toLocation)

you could calculate the distances for each pin in a for cycle, so to find the slower one

take a look at this: Find nearest annotations from user location ios?

Answer 3

You might look at something like the Mapbox Distance API to do this in a single REST request: https://www.mapbox.com/blog/distance-api/