Reverse geocode a location

When the map is long pressed, the coordinates of the gesture are sent to the reverse geocoding service. If successful, a marker with an info window containing the result is added to the map.

Get started

Before you can try the sample code, you must configure your development environment. For more information, see Maps SDK for iOS code samples.

View the code

Swift

import GoogleMaps
import UIKit

// Sample code for GeoCoder service.
class GeocoderViewController: UIViewController {

  private lazy var mapView: GMSMapView = {
    let camera = GMSCameraPosition(latitude: -33.868, longitude: 151.2086, zoom: 12)
    return GMSMapView(frame: .zero, camera: camera)
  }()

  private lazy var geocoder = GMSGeocoder()

  override func loadView() {
    view = mapView
    mapView.delegate = self
  }
}

extension GeocoderViewController: GMSMapViewDelegate {
  func mapView(_ mapView: GMSMapView, didLongPressAt coordinate: CLLocationCoordinate2D) {
    // On a long press, reverse geocode this location.
    geocoder.reverseGeocodeCoordinate(coordinate) { response, error in
      guard let address = response?.firstResult() else {
        let errorMessage = error.map { String(describing: $0) } ?? "<no error>"
        print(
          "Could not reverse geocode point (\(coordinate.latitude), \(coordinate.longitude)): \(errorMessage)"
        )
        return
      }
      print("Geocoder result: \(address)")
      let marker = GMSMarker(position: address.coordinate)
      marker.appearAnimation = .pop
      marker.map = mapView

      guard let lines = address.lines, let title = lines.first else { return }
      marker.title = title
      if lines.count > 1 {
        marker.snippet = lines[1]
      }
    }
  }
}
GeocoderViewController.swift
      

Objective-C

#import "GoogleMapsDemos/Samples/GeocoderViewController.h"

#import <GoogleMaps/GoogleMaps.h>

@implementation GeocoderViewController {
  GMSMapView *_mapView;
  GMSGeocoder *_geocoder;
}

- (void)viewDidLoad {
  [super viewDidLoad];
  GMSCameraPosition *camera = [GMSCameraPosition cameraWithLatitude:-33.868
                                                          longitude:151.2086
                                                               zoom:12];

  _mapView = [GMSMapView mapWithFrame:CGRectZero camera:camera];
  _mapView.delegate = self;

  _geocoder = [[GMSGeocoder alloc] init];

  self.view = _mapView;
}

- (void)mapView:(GMSMapView *)mapView didLongPressAtCoordinate:(CLLocationCoordinate2D)coordinate {
  // On a long press, reverse geocode this location.
  __weak __typeof__(self) weakSelf = self;
  GMSReverseGeocodeCallback handler = ^(GMSReverseGeocodeResponse *response, NSError *error) {
    [weakSelf handleResponse:response coordinate:coordinate error:error];
  };
  [_geocoder reverseGeocodeCoordinate:coordinate completionHandler:handler];
}

- (void)handleResponse:(nullable GMSReverseGeocodeResponse *)response
            coordinate:(CLLocationCoordinate2D)coordinate
                 error:(nullable NSError *)error {
  GMSAddress *address = response.firstResult;
  if (address) {
    NSLog(@"Geocoder result: %@", address);

    GMSMarker *marker = [GMSMarker markerWithPosition:address.coordinate];
    NSArray<NSString *> *lines = [address lines];

    marker.title = [lines firstObject];
    if (lines.count > 1) {
      marker.snippet = [lines objectAtIndex:1];
    }

    marker.appearAnimation = kGMSMarkerAnimationPop;
    marker.map = _mapView;
  } else {
    NSLog(@"Could not reverse geocode point (%f,%f): %@", coordinate.latitude, coordinate.longitude,
          error);
  }
}

@end
GeocoderViewController.m
      

Run the full sample app locally

The Maps SDK for iOS sample app is available as a download archive from GitHub. Follow these steps to install and try the Maps SDK for iOS sample app.

1. Run git clone https://github.com/googlemaps-samples/maps-sdk-for-ios-samples.git to clone the samples repository into a local directory.

2. Open a terminal window, navigate to the directory where you cloned the sample files, and drill down into the GoogleMaps directory:

   Swift

   cd maps-sdk-for-ios-samples-main/GoogleMaps-Swift
   pod install
   open GoogleMapsSwiftDemos.xcworkspace

   Objective-C

   cd maps-sdk-for-ios-samples-main/GoogleMaps
   pod install
   open GoogleMapsDemos.xcworkspace

3. In Xcode, press the compile button to build the app with the current scheme. The build produces an error, prompting you to enter your API key in the SDKConstants.swift file for Swift orSDKDemoAPIKey.h file for Objective-C.
4. If you don't yet have an API key, follow the instructions to set up a project on the Google Cloud console and get an API key. When configuring the key on the Cloud console, you can restrict the key to the sample app's bundle identifier to ensure that only your app can use the key. The default bundle identifier of the SDK samples app is com.example.GoogleMapsDemos.
5. Edit the SDKConstants.swift file for Swift orSDKDemoAPIKey.h file for Objective-C and paste your API key into the definition of either the apiKey or kAPIKey constant. For example:

   Swift

   static let apiKey = "YOUR_API_KEY"

   Objective-C

   static NSString *const kAPIKey = @"YOUR_API_KEY";

6. In the SDKConstants.swift file (Swift) orSDKDemoAPIKey.h file (Objective-C), remove the following line, because it's used to register the user-defined issue:

   Swift

   #error (Register for API Key and insert here. Then delete this line.)

   Objective-C

   #error Register for API Key and insert here.

7. Build and run the project. The iOS simulator window appears, showing a list of Maps SDK Demos.
8. Choose one of the options displayed, to experiment with a feature of the Maps SDK for iOS.
9. If prompted to allow GoogleMapsDemos to access your location, choose Allow.