Article

Converting a User's Location to a Descriptive Placemark

Transform the user’s location displayed on a map into an informative description.

Overview

You can show a user’s location on a map in order to orient them to elements of your app that use map content. For instance, a user’s current location can be a point of reference for retrieving search results or calculating directions. Additionally, you can display location information outside of the map, such as a search field pre-filled with the user’s current city or street address. To provide this information in your app, configure your map view to display the user’s location, and then translate the location to informative, user-friendly data.

Display the User Location Annotation

To provide user-friendly place information, configure your map view to display the user’s current location by enabling showsUserLocation. After enabling this property, the map delegate begins receiving updates to the user’s location, represented with a MKUserLocation object, through mapView:didUpdateUserLocation:.

Geocode the User Location Annotation

CLPlacemark objects represent user place names, and include properties for street name, city name, country name, and many other location identifiers. When mapView:didUpdateUserLocation: receives updates on the user’s location, convert the MKUserLocation object to a CLPlacemark by reverse geocoding the location property with a CLGeocoder. Readable descriptions of the user’s location are available as properties on the placemark, such as the city information stored in the locality property.

func mapView(_ mapView: MKMapView, didUpdate userLocation: MKUserLocation) {
        guard let newLocation = userLocation.location else { return }
        
        let currentTime = Date()
        let lastLocation = self.currentLocation
        self.currentLocation = newLocation
        
        // Only get new placemark information if you don't have a previous location,
        // if the user has moved a meaningful distance from the previous location, such as 1000 meters,
        // and if it's been 60 seconds since the last geocode request.
        if let lastLocation = lastLocation,
            newLocation.distance(from: lastLocation) <= 1000,
            let lastTime = lastGeocodeTime,
            currentTime.timeIntervalSince(lastTime) < 60 {
            return
        }
        
        // Convert the user's location to a user-friendly place name by reverse geocoding the location.
        lastGeocodeTime = currentTime
        geocoder.reverseGeocodeLocation(newLocation) { (placemarks, error) in
            guard error == nil else {
                self.handleError(error)
                return
            }
            
            // Most geocoding requests contain only one result.
            if let firstPlacemark = placemarks?.first {
                self.mostRecentPlacemark = firstPlacemark
                self.currentCity = firstPlacemark.locality
            }
        }
    }

See Also

Displaying the User’s Location

showsUserLocation

A Boolean value indicating whether the map should try to display the user’s location.

userLocationVisible

A Boolean value indicating whether the device’s current location is visible in the map view.

userLocation

The annotation object representing the user’s current location.

userTrackingMode

The mode used to track the user location.

- setUserTrackingMode:animated:

Sets the mode used to track the user location with optional animation.

MKUserTrackingMode

The mode used to track the user location on the map.