The core component of Navmii SDK responsible for route navigation is NMRouteNavigator. This class provides the API to control the route navigation process, to get navigation information and guidance updates. The class is also able to handle the rerouting and the rerouting by traffic.

CREATING ROUTE NAVIGATOR

NMSdk class contains the routeNavigator property providing access to the instance of NMRouteNavigator. The route navigator instance can be accessed only after the SDK was started.

USING ROUTE NAVIGATOR

Route navigator has different responsibilities all related to each other:

• route navigator performs navigation along the specified route. Route navigator gets GPS position updates internally, updates the route navigation state and notifies if any changes occur.
• route navigator is able to handle rerouting. This option is intended to ease handling the rerouting process for SDK user. If rerouting handling is enabled, navigator, once rerouting is required, notifies that rerouting has started, calculates a new route, starts navigating along the new route and notifies that new route navigation has started.
• route navigator is able to handle rerouting by traffic. This option is intended to ease handing the rerouting by traffic process for SDK user. If rerouting by traffic is enabled, navigator, once traffic has been updated, applies it to the current route, if possible, or builds a new route otherwise, builds alternative routes if possible, and notifies that new route navigation has started, traffic was updated and alternative routes are available.
• route navigator is able to visualize changes in route by emitting route visualizer requests. To achieve such a behaviour you need to connect the route visualizer (routeVisualizer property of NMSdk) to route navigator using addRouteVisualizerRequestListener: method of NMRouteNavigator.

ROUTE NAVIGATION

Route navigation starts by calling the startNavigatingTheRoute: method. The route parameter is an NMRoute class instance which represents the route to navigate. The source of routes is Routing Service. After the route navigation was started, route navigator gets GPS position updates internally, updates the route navigation state and notifies if any changes occur. Those notifications can be gotten by conforming to NMRouteNavigationListener protocol. Notifications about the following events are available:

• the 'on-route state' changes: user has got off the route or back on the route. The SDK user may need this information to handle rerouting manually;
• position on route (distance or time to destination) changes;
• the next direction information or distance to it changes;
• a waypoint has been passed or destination has been reached.

Route navigator has properties to access the latest route navigation information at any time.

Route navigator also provides route navigation guidance which can be gotten by conforming to NMGuidanceListener protocol.

User is able to stop route navigation by calling the stopNavigation method.

AUTOMATIC REROUTING HANDLING

As mentioned above NMRouteNavigator is able to handle rerouting automatically. The feature is enabled by default, but NMRouteNavigator class has the reroutingEnabled property which can be used to disable or enable the feature. If automatic rerouting handling is enabled, route navigator tracks on-route state and, once user is off the route being navigated, calculates new route and applies it. User gets notifications about the automatic rerouting handling process by conforming to NMReroutingListener protocol. The protocol has the onReroutingStarted which is called once automatic rerouting handling process starts and the onReroutingFinished: method which is called once the process finishes. The onReroutingFinished: method has the newRoute parameter which is the new NMRoute class instance representing new route being navigated. newRoute can be nil if rerouting handling is no longer required (i.e. user returned back to the previous route).

Rerouting engine has an algorithm which attempts to use the route similar to the one user initially started to navigate by calling the startNavigatingTheRoute: method. NMRouteNavigator has the reroutingSettings which allows user to tune the algorithm a bit.

AUTOMATIC REROUTING BY TRAFFIC HANDLING

As mentioned above NMRouteNavigator is able to handle rerouting by traffic automatically. The feature is enabled by default, but NMRouteNavigator class has the reroutingByTrafficEnabled property which can be used to disable or enable the feature. If automatic rerouting by traffic handling is enabled, route navigator internally get notifications from traffic service that traffic near current position was updated, and, once it happens, handles rerouting by traffic. User gets notifications about rerouting by traffic handling by conforming to NMReroutingByTrafficListener protocol. The protocol has the single method which is called once rerouting by traffic occurred. Here it is:

- (void)onReroutingByTrafficOccurredWithOldTimeToDestination:(NSInteger)oldTimeToDestinationInSeconds
                                        newTimeToDestination:(NSInteger)newTimeToDestinationInSeconds
                                                    newRoute:(nullable NMRoute *)newRoute
                                          resemblingOldRoute:(BOOL)doesNewRouteResembleOldOne
                                           alternativeRoutes:(nullable NSArray<NMRoute *> *)alternativeRoutes;

Rerouting by traffic engine may change NMRoute class instance used for navigation during rerouting by traffic handling. newRoute will have non-null value if that happens. doesNewRouteResembleOldOne parameter indicates whether route being navigated after rerouting by traffic occurred is identical (takes the same roads) to the route being navigated before that. So, even if newRoute is non-null but doesNewRouteResembleOldOne is YES, what that means is route being navigated hasn't changed (takes the same roads).

alternativeRoutes is the list of alternative routes with the latest traffic applied which can be used by user for navigation. To use one of alternative routes for navigation user need to call startNavigatingTheRoute: method.