Swift 4 MapKit check if mark is near to my location

Question

I want to check when my position is changing if my location is near the Mark. I have marks with unique position. If i near for example 10m from mark i want to display alert. How i can do that?

Answer 1

1. Get visible annotations.
2. Calculate distance between your position and the mark.

e.g.

func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
    guard let myLocation = locations.first else { return }

    let annotationSet = mapView.annotations(in: mapView.visibleMapRect)
    for annotation in annotationSet {
        guard let annotation = annotation as? MKPointAnnotation else { continue }
        let loc = CLLocation(latitude: annotation.coordinate.latitude,
                             longitude: annotation.coordinate.longitude)
        let distance = myLocation.distance(from: loc)
        if distance < 10.0 { Show Alert }
        }
    }
}