Details about the turn-by-turn data feed

A turn-by-turn data feed provides navigation-only information to devices not designed for map-based navigation guidance. It provides upcoming maneuvers with elements you supply:

  • icons (left, right, U-turn)
  • turn numbers in roundabouts
  • road names
  • estimated distances and time to the next navigation step or final destination

You can use the turn-by-turn feed to create experiences where the full Navigation SDK UI is not appropriate, such as for small screen displays. For example, you might use this for two-wheeled vehicle riders, where you can project navigation-only guidance to help them reach their destinations faster and more confidently with minimal distractions.

Essential navigation display elements

A mobile screen that displays an upcoming right turn in 50 feet onto Church Street. At the bottom of the screen, time remaining to destination is 13 minutes, and distance remaining is 2.1 miles.

The primary fields for each navigation step are the full road name, maneuver, and total distance of the step, which are available in GMSNavigationStepInfo.

For the overall trip, you may want to display the remaining time and distance to the current step or to the destination, all of which are available in GMSNavigationNavInfo. The image to the right shows an example of these essential navigation elements.

Set up an event listener

To use navigation-only data, you have to implement an event listener for the didChangeNavInfo event. Within the event listener, access trip and step information to provide turn by turn navigation to your users.

To implement event handlers, the view controller of the map must implement the GMSNavigatorListener protocol. For detailed information on handling events in the Navigation SDK for iOS, see Listen for navigation events.

Handling the didChangeNavInfo event

Create a listener for the didChangeNavInfo event to add turn-by-turn support to your app. In the event listener, use the following classes and enums to control turn-by-turn navigation:

Shown below are example event listeners for the didChangeNavInfo event:

SwiftObjective-C 
  // ViewController.swift
  class SomeViewController: UIViewController {
    ...
    mapView.navigator?.add(self);
    ...
  }

  extension SomeViewController: GMSNavigatorListener {
    func navigator(_ navigator: GMSNavigator,
                   didUpdateNavInfo navInfo: GMSNavigationNavInfo) {

      // Get the current step information
      if navInfo.navState == .enroute {
        if let currentStep = navInfo.currentStep {
          ...
          roadNameLabel.text = currentStep.simpleRoadName
          ...
        }
      }
    }
  }
  // ViewController.h
  @interface SomeViewController () <GMSNavigatorListener>

  @end

  // ViewController.m
  @implementation SomeViewController
  // Some initialization code.
  ... {
    ...
    [_mapView.navigator addListener:self];
    ...
  }

  #pragma mark GMSNavigatorListener
  - (void)navigator:(GMSNavigator *)navigator didUpdateNavInfo:(GMSNavigationNavInfo *)navInfo {
    // Get the current step information
    if (navInfo.navState == GMSNavigationNavStateEnroute) {
      GMSNavigationStepInfo *currentStep = navInfo.currentStep;
      if (currentStep) {
        ...
        roadNameLabel.text = currentStep.simpleRoadName;
        ...
      }
    }
    ...
  }

Use navState property of GMSNavigationNavInfo to get the current state of navigation, which is one of the following:

  • Enroute - The GMSNavigationNavStateEnroute state means that guided navigation is currently active and the user is on the provided route. Information about the current upcoming maneuver step is available.

  • Rerouting - GMSNavigationNavStateRerouting means that navigation is in progress, but the navigator is looking for a new route. The upcoming maneuver step is not available, because there's no new route yet.

  • Stopped - GMSNavigationNavStateStopped means navigation has ended. For example, navigation stops when the user exits navigation in the app. In the sample app, a GMSNavigationNavStateStopped state clears the navigation info display to prevent lingering step instructions from being displayed.

Lane guidance

The Navigation SDK represents lanes in the navigation turn card as GMSNavigationLane and GMSNavigationLaneDirection data objects. A GMSNavigationLane object represents a specific lane during navigation and has a list of GMSNavigationLaneDirection objects that describe all the turns that can be made from this lane.

The recommended direction a driver should take in a lane is marked using the recommended field.

Lane guidance example

The following snippet illustrates the data representation of the lanes displayed in the preceding screenshot.

// Lane 1
GMSNavigationLaneDirections =
  [{/*GMSNavigationLaneShape=*/
GMSNavigationLaneShapeNormalLeft, /*recommended=*/ true}]

// Lane 2
GMSNavigationLaneDirections =
  [{/*GMSNavigationLaneShape=*/
GMSNavigationLaneShapeNormalLeft, /*recommended=*/ true}]

// Lane 3
GMSNavigationLaneDirections =
  [{/*GMSNavigationLaneShape=*/
GMSNavigationLaneShapeStraight, /*recommended=*/ false}]

// Lane 4
GMSNavigationLaneDirections =
  [{/*GMSNavigationLaneShape=*/
GMSNavigationLaneShapeStraight, /*recommended=*/ false},
{/*GMSNavigationLaneShape=*/ GMSNavigationLaneShapeNormalRight, /*recommended=*/ false}]

Lane guidance images

The Navigation SDK supports generation of lane images for each navigation step as conveyed by GMSNavigationStepInfo. These icons fit CarPlay's image sizing guidance.

SwiftObjective-C 
let currentStepInfo = navInfo.currentStep

let options = GMSNavigationStepImageOptions()
options.maneuverImageSize = .square96
options.screenMetrics = UIScreen.mainScreen

let maneuverImage = currentStepinfo.maneuverImage(options: options)
      
GMSNavigationStepInfo *stepInfo = navInfo.currentStep;

GMSNavigationStepImageOptions *options = [[GMSNavigationStepImageOptions alloc] init];
options.maneuverImageSize = GMSNavigationManeuverImageSizeSquare96;
options.screenMetrics = UIScreen.mainScreen;

UIImage* maneuverImage = [stepInfo maneuverImageWithOptions:options];

Creating icons for maneuvers

maneuver icon

The GMSNavigationManeuver enum defines each possible maneuver that could occur while navigating, and you can get the maneuver for a given step from the maneuver property of GMSNavigationStepInfo.

You must create maneuver icons and pair them with their associated maneuvers. For some maneuvers, you can set up a one-to-one mapping to an icon, such as GMSNavigationManeuverDestinationLeft and GMSNavigationManeuverDestinationRight. However, since some maneuvers share characteristics with other maneuvers, you might want to map more than one maneuver to a single icon. For example GMSNavigationManeuverTurnLeft and GMSNavigationManeuverOnRampLeft could both map to the left turn icon.

Some maneuvers contain an additional "Clockwise" or "CounterClockwise" label, which the SDK determines based on the driving side of a country. For example, in countries where driving is on the left side of the road, drivers take a roundabout or U-turn in a clockwise direction, whereas right-side-of-the-road countries go counterclockwise. The Navigation SDK detects whether a maneuver occurs in left- or right-side traffic and outputs the appropriate maneuver. Therefore, your maneuver icon may be different for a clockwise versus a counterclockwise maneuver.

Sample Icon Turn-By-Turn Maneuvers
DEPART
UNKNOWN
STRAIGHT
ON_RAMP_UNSPECIFIED
OFF_RAMP_UNSPECIFIED
NAME_CHANGE
TURN_RIGHT
ON_RAMP_RIGHT
TURN_LEFT
ON_RAMP_LEFT
TURN_SLIGHT_RIGHT
ON_RAMP_SLIGHT_RIGHT
OFF_RAMP_SLIGHT_RIGHT
TURN_SLIGHT_LEFT
ON_RAMP_SLIGHT_LEFT
OFF_RAMP_SLIGHT_LEFT
TURN_SHARP_RIGHT
ON_RAMP_SHARP_RIGHT
OFF_RAMP_SHARP_RIGHT
TURN_SHARP_LEFT
ON_RAMP_SHARP_LEFT
OFF_RAMP_SHARP_LEFT
TURN_U_TURN_COUNTERCLOCKWISE
ON_RAMP_U_TURN_COUNTERCLOCKWISE
OFF_RAMP_U_TURN_COUNTERCLOCKWISE
TURN_U_TURN_CLOCKWISE
ON_RAMP_U_TURN_CLOCKWISE
OFF_RAMP_U_TURN_CLOCKWISE
ROUNDABOUT_SHARP_RIGHT_COUNTERCLOCKWISE
ROUNDABOUT_SHARP_RIGHT_CLOCKWISE
ROUNDABOUT_RIGHT_COUNTERCLOCKWISE
ROUNDABOUT_RIGHT_CLOCKWISE
ROUNDABOUT_SLIGHT_RIGHT_COUNTERCLOCKWISE
ROUNDABOUT_SLIGHT_RIGHT_CLOCKWISE
ROUNDABOUT_STRAIGHT_COUNTERCLOCKWISE
ROUNDABOUT_STRAIGHT_CLOCKWISE
ROUNDABOUT_SLIGHT_LEFT_COUNTERCLOCKWISE
ROUNDABOUT_SLIGHT_LEFT_CLOCKWISE
ROUNDABOUT_LEFT_COUNTERCLOCKWISE
ROUNDABOUT_LEFT_CLOCKWISE
ROUNDABOUT_SHARP_LEFT_COUNTERCLOCKWISE
ROUNDABOUT_SHARP_LEFT_CLOCKWISE
ROUNDABOUT_U_TURN_COUNTERCLOCKWISE
ROUNDABOUT_U_TURN_CLOCKWISE
ROUNDABOUT_COUNTERCLOCKWISE
ROUNDABOUT_CLOCKWISE
ROUNDABOUT_EXIT_COUNTERCLOCKWISE
ROUNDABOUT_EXIT_CLOCKWISE
MERGE_RIGHT
OFF_RAMP_RIGHT
MERGE_LEFT
OFF_RAMP_LEFT
FORK_RIGHT
TURN_KEEP_RIGHT
ON_RAMP_KEEP_RIGHT
OFF_RAMP_KEEP_RIGHT
FORK_LEFT
TURN_KEEP_LEFT
ON_RAMP_KEEP_LEFT
OFF_RAMP_KEEP_LEFT
MERGE_UNSPECIFIED
DESTINATION
DESTINATION_RIGHT
DESTINATION_LEFT
FERRY_BOAT
FERRY_TRAIN

Use generated icons

The Navigation SDK supports generation of maneuver icons for a given GMSNavigationStepInfo. These icons fit CarPlay image sizing guidance.

SwiftObjective-C 
let currentStepInfo = navInfo.currentStep

let options = GMSNavigationStepImageOptions()
options.maneuverImageSize = .square96
options.screenMetrics = UIScreen.mainScreen

let maneuverImage = currentStepinfo.maneuverImage(options: options)
      
GMSNavigationStepInfo *stepInfo = navInfo.currentStep;

GMSNavigationStepImageOptions *options = [[GMSNavigationStepImageOptions alloc] init];
options.maneuverImageSize = GMSNavigationManeuverImageSizeSquare96;
options.screenMetrics = UIScreen.mainScreen;

UIImage* maneuverImage = [stepInfo maneuverImageWithOptions:options];