Markers

Markers indicate single locations on the map.

By default, markers use a standard icon that has the common Google Maps look and feel. If you want to customize your marker, you can change the color of the default marker, or replace the marker image with a custom icon, or change other properties of the marker.

Adding a marker

To add a marker, create a GMSMarker object that includes a position and title, and set its map.

The following example demonstrates how to add a marker to an existing GMSMapView object. The marker is created at coordinates 10,10, and displays the string "Hello world" in an info window when clicked.

let position = CLLocationCoordinate2D(latitude: 10, longitude: 10)
let marker = GMSMarker(position: position)
marker.title = "Hello World"
marker.map = mapView
      

CLLocationCoordinate2D position = CLLocationCoordinate2DMake(10, 10);
GMSMarker *marker = [GMSMarker markerWithPosition:position];
marker.title = @"Hello World";
marker.map = mapView;
      

You can animate the addition of new markers to the map by setting the marker.appearAnimation property to:

• kGMSMarkerAnimationPop to cause the marker to pop from its groundAnchor when added.
• kGMSMarkerAnimationFadeIn to cause the marker to fade in when added.

Removing a marker

You can remove a marker from the map by setting the map property of the GMSMarker to nil. Alternatively, you can remove all of the overlays (including markers) currently on the map by calling the GMSMapView clear method.

let camera = GMSCameraPosition.camera(
  withLatitude: -33.8683,
  longitude: 151.2086,
  zoom: 6
)
let mapView = GMSMapView.map(withFrame: .zero, camera: camera)
// ...
mapView.clear()
      

GMSCameraPosition *camera = [GMSCameraPosition cameraWithLatitude:-33.8683
                                                        longitude:151.2086
                                                             zoom:6];
mapView = [GMSMapView mapWithFrame:CGRectZero camera:camera];
// ...
[mapView clear];
      

If you wish to make modifications to a marker after you've added it to the map, ensure that you keep hold of the GMSMarker object. You can modify the marker later by making changes to this object.

let position = CLLocationCoordinate2D(latitude: 10, longitude: 10)
let marker = GMSMarker(position: position)
marker.map = mapView
// ...
marker.map = nil
      

CLLocationCoordinate2D position = CLLocationCoordinate2DMake(10, 10);
GMSMarker *marker = [GMSMarker markerWithPosition:position];
marker.map = mapView;
// ...
marker.map = nil;
      

Changing the marker color

You can customize the color of the default marker image by requesting a tinted version of the default icon with markerImageWithColor:, and passing the resulting image to the GMSMarker's icon property.

marker.icon = GMSMarker.markerImage(with: .black)
      

marker.icon = [GMSMarker markerImageWithColor:[UIColor blackColor]];
      

Customizing the marker image

If you want to change the default marker image you can set a custom icon, using the marker's icon or iconView property.

If iconView is set, the API ignores the icon property. Updates to the current icon are not recognised as long as the iconView is set.

Using the marker's `icon` property

The following snippet creates a marker with a custom icon provided as a UIImage in the icon property. The icon is centered at London, England. The snippet assumes that your application contains an image named "house.png".

let positionLondon = CLLocationCoordinate2D(latitude: 51.5, longitude: -0.127)
let london = GMSMarker(position: positionLondon)
london.title = "London"
london.icon = UIImage(named: "house")
london.map = mapView
      

CLLocationCoordinate2D positionLondon = CLLocationCoordinate2DMake(51.5, -0.127);
GMSMarker *london = [GMSMarker markerWithPosition:positionLondon];
london.title = @"London";
london.icon = [UIImage imageNamed:@"house"];
london.map = mapView;
      

If you are creating several markers with the same image, use the same instance of UIImage for each of the markers. This helps improve the performance of your application when displaying many markers.

This image may have multiple frames. Additionally, the alignmentRectInsets property is respected, which is useful if a marker has a shadow or other unusable region.

Using the marker's `iconView` property

The following snippet creates a marker with a custom icon by setting the marker's iconView property, and animates a change in the color of the marker. The snippet assumes that your application contains an image named "house.png".

import CoreLocation
import GoogleMaps

class MarkerViewController: UIViewController, GMSMapViewDelegate {
  var mapView: GMSMapView!
  var london: GMSMarker?
  var londonView: UIImageView?

  override func viewDidLoad() {
    super.viewDidLoad()

    let camera = GMSCameraPosition.camera(
      withLatitude: 51.5,
      longitude: -0.127,
      zoom: 14
    )
    let mapView = GMSMapView.map(withFrame: .zero, camera: camera)
    view = mapView

    mapView.delegate = self

    let house = UIImage(named: "House")!.withRenderingMode(.alwaysTemplate)
    let markerView = UIImageView(image: house)
    markerView.tintColor = .red
    londonView = markerView

    let position = CLLocationCoordinate2D(latitude: 51.5, longitude: -0.127)
    let marker = GMSMarker(position: position)
    marker.title = "London"
    marker.iconView = markerView
    marker.tracksViewChanges = true
    marker.map = mapView
    london = marker
  }

  func mapView(_ mapView: GMSMapView, idleAt position: GMSCameraPosition) {
    UIView.animate(withDuration: 5.0, animations: { () -> Void in
      self.londonView?.tintColor = .blue
    }, completion: {(finished) in
      // Stop tracking view changes to allow CPU to idle.
      self.london?.tracksViewChanges = false
    })
  }
}
      

@import CoreLocation;
@import GoogleMaps;

@interface MarkerViewController : UIViewController <GMSMapViewDelegate>
@property (strong, nonatomic) GMSMapView *mapView;
@end

@implementation MarkerViewController {
  GMSMarker *_london;
  UIImageView *_londonView;
}

- (void)viewDidLoad {
  [super viewDidLoad];

  GMSCameraPosition *camera = [GMSCameraPosition cameraWithLatitude:51.5
                                                          longitude:-0.127
                                                               zoom:14];
  _mapView = [GMSMapView mapWithFrame:CGRectZero camera:camera];
  self.view = _mapView;

  _mapView.delegate = self;

  UIImage *house = [UIImage imageNamed:@"House"];
  house = [house imageWithRenderingMode:UIImageRenderingModeAlwaysTemplate];
  _londonView = [[UIImageView alloc] initWithImage:house];
  _londonView.tintColor = [UIColor redColor];

  CLLocationCoordinate2D position = CLLocationCoordinate2DMake(51.5, -0.127);
  _london = [GMSMarker markerWithPosition:position];
  _london.title = @"London";
  _london.iconView = _londonView;
  _london.tracksViewChanges = YES;
  _london.map = self.mapView;
}

- (void)mapView:(GMSMapView *)mapView idleAtCameraPosition:(GMSCameraPosition *)position {
  [UIView animateWithDuration:5.0
                   animations:^{
    self->_londonView.tintColor = [UIColor blueColor];
  }
                   completion:^(BOOL finished) {
    // Stop tracking view changes to allow CPU to idle.
    self->_london.tracksViewChanges = NO;
  }];
}

@end
      

Because iconView accepts a UIView, you can have a hierarchy of standard UI controls defining your markers, each view having the standard set of animation capabilities. You can include changes to the marker size, color, and alpha levels, as well as applying arbitrary transformations. The iconView property supports animation of all animatable properties of UIView except frame and center.

Please note the following considerations when using iconView:

• The UIView can be demanding on resources when tracksViewChanges is set to YES, which may result in increased battery usage. In comparison, a single frame UIImage is static and does not need to be re-rendered.
• Some devices may struggle to render the map if you have many markers on screen, and each marker has its own UIView, and all markers are tracking changes at the same time.
• An iconView does not respond to user interaction, as it is a snapshot of the view.
• The view behaves as if clipsToBounds is set to YES, regardless of its actual value. You can apply transforms that work outside the bounds, but the object you draw must be within the bounds of the object. All transforms/shifts are monitored and applied. In short: subviews must be contained within the view.

To decide when to set the tracksViewChanges property, you should weigh up performance considerations against the advantages of having the marker redrawn automatically. For example:

• If you have a series of changes to make, you can change the property to YES then back to NO.
• When an animation is running or the contents are being loaded asynchronously, you should keep the property set to YES until the actions are complete.

Changing the marker opacity

You can control the opacity of a marker with its opacity property. You should specify the opacity as a float between 0.0 and 1.0, where 0 is fully transparent and 1 is fully opaque.

marker.opacity = 0.6
      

marker.opacity = 0.6;
      

You can animate the marker opacity with Core Animation via the GMSMarkerLayer.

Flattening a marker

Marker icons are normally drawn oriented against the device's screen rather than the map's surface, so rotating, tilting or zooming the map does not necessarily change the orientation of the marker.

You can set the orientation of a marker to be flat against the earth. Flat markers rotate when the map is rotated, and change perspective when the map is tilted. As with regular markers, flat markers retain their size when the map is zoomed in or out.

To change the orientation of the marker, set the marker's flat property to YES or true.

let positionLondon = CLLocationCoordinate2D(latitude: 51.5, longitude: -0.127)
let londonMarker = GMSMarker(position: positionLondon)
londonMarker.isFlat = true
londonMarker.map = mapView
      

CLLocationCoordinate2D positionLondon = CLLocationCoordinate2DMake(51.5, -0.127);
GMSMarker *londonMarker = [GMSMarker markerWithPosition:positionLondon];
londonMarker.flat = YES;
londonMarker.map = mapView;
      

Rotating a marker

You can rotate a marker around its anchor point by setting the rotation property. Specify the rotation as a CLLocationDegrees type, measured in degrees clockwise from the default position. When the marker is flat on the map, the default position is North.

The following example rotates the marker 90°. Setting the groundAnchor property to 0.5,0.5 causes the marker to be rotated around its center, instead of its base.

let degrees = 90.0
londonMarker.groundAnchor = CGPoint(x: 0.5, y: 0.5)
londonMarker.rotation = degrees
londonMarker.map = mapView
      

CLLocationDegrees degrees = 90;
londonMarker.groundAnchor = CGPointMake(0.5, 0.5);
londonMarker.rotation = degrees;
londonMarker.map = mapView;
      

Adding an info window

Use an info window to display information to the user when they tap on a marker. Only one info window is displayed at a time. If a user taps on another marker, the current window is hidden and the new info window opens. The contents of the info window are defined by the title and snippet properties. Clicking the marker does not display an info window if both the title and snippet properties are blank or nil.

The following snippet creates a simple marker, with only a title for the text of the info window.

let position = CLLocationCoordinate2D(latitude: 51.5, longitude: -0.127)
let london = GMSMarker(position: position)
london.title = "London"
london.map = mapView
      

CLLocationCoordinate2D position = CLLocationCoordinate2DMake(51.5, -0.127);
GMSMarker *london = [GMSMarker markerWithPosition:position];
london.title = @"London";
london.map = mapView;
      

With the snippet property, you can add additional text that will appear below the title in a smaller font. Strings that are longer than the width of the info window are automatically wrapped over several lines. Very long messages may be truncated.

london.title = "London"
london.snippet = "Population: 8,174,100"
london.map = mapView
      

london.title = @"London";
london.snippet = @"Population: 8,174,100";
london.map = mapView;
      

Setting an info window to refresh automatically

Set tracksInfoWindowChanges on the marker to YES or true if you want new properties or the content of the info window to be immediately displayed when changed, rather than having to wait for the info window to hide and then show again. The default is NO or false.

london.tracksInfoWindowChanges = true
      

london.tracksInfoWindowChanges = YES;
      

To decide when to set the tracksInfoWindowChanges property, you should weigh up performance considerations against the advantages of having the info window redrawn automatically. For example:

• If you have a series of changes to make, you can change the property to YES then back to NO.
• When an animation is running or the contents are being loaded asynchronously, you should keep the property set to YES until the actions are complete.

Refer also to the notes for consideration when using the iconView property of the marker.

Changing the position of an info window

An info window is drawn oriented against the device's screen, centered above its associated marker. You can alter the position of the info window relative to the marker by setting the infoWindowAnchor property. This property accepts a CGPoint, defined as an (x,y) offset where both x and y range between 0.0 and 1.0. The default offset is (0.5, 0.0), that is, the center top. Setting the infoWindowAnchor offset is useful for aligning the info window against a custom icon.

london.infoWindowAnchor = CGPoint(x: 0.5, y: 0.5)
london.icon = UIImage(named: "house")
london.map = mapView
      

london.infoWindowAnchor = CGPointMake(0.5, 0.5);
london.icon = [UIImage imageNamed:@"house"];
london.map = mapView;
      

Handling events on markers and info windows

You can listen to events that occur on the map, such as when a user taps a marker or an info window. To listen to events, you must implement the GMSMapViewDelegate protocol. See the guide to events and the list of methods on the GMSMapViewDelegate. For Street View events, see the GMSPanoramaViewDelegate.