The core component of Navmii SDK responsible for route calculation is NMRoutingService. This class provides the API for calculating new routes and snapping external routes to the map.
CREATING ROUTING SERVICE
NMSdk class contains routingService
property which allows Navmii SDK user to access routing service instance. The routing service instance can only be created after the SDK was started.
It's the SDK user's responsibility to make sure that routing service instance exists during the route calculation process, therefore you should NOT release the routing service instance until all the desired requests finish.
Here is an example of routing service creation.
ROUTING SERVICE BASICS
Routing service can be used to calculate new routes or to snap external routes to the map. Routing service handles both processes in the same way.
Successful route calculation or snapping result is the route or the list of routes each of which is represented by NMRoute class instance. Those routes can be used by other SDK modules: they can be rendered on map or used for navigation.
Once routing service is requested to calculate or snap a route, it returns a route calculation session represented by NMRouteCalculationSession class instance. Route calculation session is the routing service request handler which is used to control the request.
Since session is the only way to control the associated calculation request, the user of the routing service should NOT release the session object until the request finishes. If the session object is released while the request is in progress, the request is canceled and the user gets no notification on its progress anymore.
NMRouteCalculationSession class instances are passive objects which you can use to request the current status and successful or failure info. You can also use it to cancel the request. In order to get the request status change notifications you can specify an object conforming to the NMRouteCalculationListener protocol withing the request to the routing service.
Basically the route calculation request can be in two states: in progress or finished. Route calculation session's hasFinished
property indicates the state.
Once you requested a new route calculation or snapping by calling the corresponding routing service method and got the session instance back, route calculation starts. At this moment session's hasFinished
property, as well as wasCanceled
, hasSucceeded
and hasFailed
, returns NO
.
The request can become finished due to the following reasons:
- route calculation has succeeded. Session's
hasFinished
property, as well ashasSucceeded
, returnsYES
.wasCanceled
andhasFailed
properties returnNO
.result
property contains valid non-null request result. Route calculation listener'sonRouteCalculationSucceededWithResult:
is called while session transits to this state. - route calculation has failed. Session's
hasFinished
property, as well ashasFailed
, returnsYES
.wasCanceled
andhasSucceeded
properties returnNO
.failureInfo
property contains valid non-null request failure info. Route calculation listener'sonRouteCalculationFailedWithInfo:
is called while session transits to this state. - route calculation was canceled by user by calling session's
cancel
method. Session'shasFinished
property, as well aswasCanceled
, returnsYES
.hasSucceeded
andhasFailed
properties returnNO
. Please note that request can only be canceled if it hasn't finished by the momentcancel
method is called. Canceling the finished session doesn't affect the request state.
As mentioned before, routing service uses NMRouteCalculationListener protocol to notify user about route calculation status changes. NMRouteCalculationListener contains three optional methods:
onRouteCalculationSucceededWithResult:
is called once route calculation succeeded.result
parameter contains valid non-null route calculation results. The fact that the method was called means the route calculation process had completely finished, therefore user won't receive any other notifications on its status changes.onRouteCalculationFailedWithInfo:
is called once route calculation failed.info
parameter contains valid non-null route failure info. The fact that the method was called means the route calculation process had completely finished, therefore user won't receive any other notifications on its status changes.onNonFatalRouteCalculationErrorOccurred:
is called once a non-fatal route error occurs during the route calculation. A non-fatal error is an error which does not result in route calculation process interruption. An example of such an error is a network error during an attempt to access routing or map tile server.error
parameter contains an error code describing the reason the method was called. The call is just a notification to the SDK user that something went wrong during the route calculation process. Since the fact that the method was called does NOT mean the route calculation process had completely finished, user should expect to see other notifications on route calculation status update.
Here is an example of route calculation request handling.
CALCULATING ROUTES
CALCULATING A ROUTE USING ROUTE PLAN
Routing service allows to calculate new routes using the specified route plan. A route plan is a list of waypoints represented by instances of NMRoutePlanPoint class. A route plan should contain at least two points.
A route plan point contains geo coordinates and optional course. Course is used by the routing engine as a hint to calculate direction to move from the point. Usually SDK users don't have such information so you don't have to specify it.
Another route plan point property is called snapped
. It indicates whether the route plan point was snapped to the map by Navmii SDK. SDK users do NOT have a way to construct the snapped route plan point other then to construct it from a snapped position returned by another SDK module. The SDK returns positions as NMPosition class instances. The class has the snapped
property as well. A route plan point will be considered as snapped if only constructed from a snapped position. In this case snapped route plan point will have course set as well.
All that means that its enough to have geo coordinates for the second and further route plan points. Nevertheless there are options for the first point. If you need to calculate a route from the current position, the preferred way to do this is to use the snapped current position to construct the first route plan point. If however you need to calculate a route starting from some random geo location, geo coordinates would be enough to construct the first route plan point.
Use snapped current position provided by Navmii SDK to construct the first route plan point if you need to calculate a route from current position. Use just coordinates to construct the first route plan point if you need to calculate route starting from some random location.
Here are example methods for both cases.
ROUTING SERVICE SETTINGS
As you can see in the examples above user is able to pass route calculation options within each routing service request. The specified options are used during request handling. If no options were passed default options are used. NMRouteCalculationOptions class instances represent available route calculation options.