MapKit- How to add location constraints for dropping a pin? - ios

Question

I have an application that allows users to drop a pin anywhere on their map (MapKit), and it currently identifies and displays their current location. I would like to set a constraint so that users are unable drop a pin any further than 10 miles from their current location. Is this doable? I am somewhat new to dev, so I am not sure where to begin doing this. Here's a bit of the code that deals with dropping pin:
#IBOutlet weak var mapView: MKMapView!
//addpin
#IBAction func addPin(sender: UILongPressGestureRecognizer) {
//locating where to drop the pin
let location = sender.locationInView(self.mapView)
let locCoord = self.mapView.convertPoint(location, toCoordinateFromView:
self.mapView)
let annotation = MKPointAnnotation()
annotation.coordinate = locCoord
annotation.title = "Test"
annotation.subtitle = "subtext"
//remove map point (use later)
self.mapView.removeAnnotations(mapView.annotations)
self.mapView.addAnnotation(annotation)
}

Answer 1

You can use distance(from: ) method.
See: https://developer.apple.com/documentation/corelocation/cllocation/1423689-distance
#IBAction func addPin(sender: UILongPressGestureRecognizer) {
//locating where to drop the pin
let location = sender.locationInView(self.mapView)
let locCoord = self.mapView.convertPoint(location, toCoordinateFromView:
self.mapView)
// Get distance between pressed location and user location
let pressedLocation = CLLocation(latitude: locCoord.latitude, longitude: locCoord.longitude)
// let distanceInMeters = self.mapView.userLocation.location?.distance(from: pressedLocation) // >= Swift 3
let distanceInMeters = self.mapView.userLocation.location?.distanceFromLocation(pressedLocation) // < Swift 3
// You get here distance in meter so 10 miles = 16090 meter
if let distanceInMeters = distanceInMeters, distanceInMeters > 16090 {
// out of 10 mile (don't drop pin)
return
}
let annotation = MKPointAnnotation()
annotation.coordinate = locCoord
annotation.title = "Test"
annotation.subtitle = "subtext"
//remove map point (use later)
self.mapView.removeAnnotations(mapView.annotations)
self.mapView.addAnnotation(annotation)
}
However, there are couple of things that you need to put in place first.
You need to ask the user for permission to use their location. That includes calling CLLocationManager's requestWhenInUseAuthorization and checking for the asynchronous result.
Adding NSLocationWhenInUseUsageDescription entry to your info (described in the link above) to tell the user what you want to do with the information