iOS documentation

The MotionTag Mobility & Location Analytics SDK collects an iPhone's raw sensor data in a battery efficient way. This data is then transmitted to the MotionTag back-end system (ISO 27001 certified). In the backend, the sensor events are processed and a partial journey is constructed. Journeys consist either solely of tracks or tracks plus stays. Tracks describe a movement from a origin to a destination with a certain mode of transport. Stays symbolize a stationary behaviour with a particular purpose for the visit.

The use cases for the SDK are manifold. In the mobility sector it can be used to get detailed mobility data for planning purposes. The collected data enables to compare how the transport network is being used. This way the effectiveness of the current infrastructure and the passenger flow management is measured and the design of new mobility services. By implementing and using the SDK you can make use of these findings to improve timetables and routes, expand transport supply and attract more passengers.

If you integrate MotionTag Tracker SDK inside your own application, you can either download user journeys via a provided dump interface on the internet or we tailor a customized solution to your needs.

1. Changelog

You can find the latest SDK version in our changelog page.

2. Native sample app

A native iOS sample app can be found on our GitHub page: https://github.com/MotionTag/motiontag-sample-app-ios This sample app showcases the best practices in integrating the SDK into native iOS apps.

3. Required App Settings

  • Activate Capabilities -> Background Modes -> Location Updates
  • Add to Info.plist:
    • "Privacy - Motion Usage Description" string
    • "Privacy - Location Always & When in Use Description" string
    • "Privacy - When in Use Description" string
  • minimum deployment target 11.0

Authorizations

The SDK requires two authorizations:

  1. Location (Always)
  2. Motion

By default both authorizations are requested from the user when you call start the first time.

Location

To function properly the SDK requires the 'Always' location permission.

If you want to request the permissions at another/earlier time you can do so by simply instantiating a CLLocationManager and calling requestAlwaysAuthorization at any time.

Motion

Unfortunately, iOS provides no such way for requesting the 'Motion authorization' - it is automatically requested when you start gathering motion data the first time.

4. Interface

public enum DataTransferMode : UInt {
    case wifiOnly
    case wifiAnd3G
}

open class MotionTagCore : NSObject {
    open class func sharedInstance(withToken token: String?, settings settingsDict: [AnyHashable : Any]?, completion: (() -> Void)? = nil) -> NSObjectProtocol & MotionTag
    open func setDelegate(_ delegate: MotionTagDelegate?)
}

public protocol MotionTagDelegate : NSObjectProtocol {
    optional func locationManager(_ locationManager: CLLocationManager, didChange status: CLAuthorizationStatus)
    optional func didTrackLocation(_ location: CLLocation)
    optional func didTransmitData(_ transmissionTimestamp: Date, lastEventTimestamp: Date) 
}

public protocol MotionTag {
    var isTrackingActive: Bool { get }
    var trackingActiveAsInt: NSNumber { get }
    weak var delegate: MotionTagDelegate? { get set }
    func start(withToken token: String?)
    func start(withToken token: String?, settings settingsDict: [AnyHashable : Any]?)
    func stop()
}

5. Setup

Initialize the library via the singleton method:

    let motionTag = MotionTagCore.sharedInstance(withToken: TOKEN_OR_NIL, settings: SETTINGS_OR_NIL){
    // continue with setup here
    }

This needs to be done somewhere near the top of didFinishLaunchingWithOptions. The reason is that the app may be started from the background by the system. By initializing the tracking library early, you guarantee that all location managers are set up to retreive new incoming locations. Since the SDK may need additional time to finalize its initialization (e.g. necessary data migrations that have to be run on startup) the init call is asynchronous. The completion block will be called by the SDK once it is done with everything. Please do not call SDK functions before this block has been run since all calls will be ignored.
The library will recognize if it has already been started and act accordingly. Please be advised that if your have acquired a valid token in a previous start, you should pass it as a parameter here, otherwise pass nil. The settings parameter can also be an NSDictionary or nil. For more info see the Settings section below.

If you want to receive callbacks, set the appropriate delegate (MotionTagDelegate):

    motionTag.delegate = self

To start tracking, just call the startWithToken:settings: method:

    motionTag.start(withToken:"A_VALID_TOKEN", settings:SETTINGS_OR_NIL)

To stop tracking, just call the stop method:

    motionTag.stop()

6. SDK Settings

Both, sharedInstance(withToken: , settings: ) and start(withToken: , settings: ) accept an NSDictionary as a parameter - if you pass in nil the SDK will fall back to default values. The settings described in this section cannot be changed while the SDK is running. So you will have stop the tracking (motionTag.stop()) before changing the settings and finally call start(withToken: , settings: ) with the modified settings to re-start the tracking. You would then also pass these modified settings into the sharedInstanceWithToken:settings:completion: method on the next start of your application - so it makes sense to persist the settings within your app.

The following options are available:

  • kMTDataTransferMode (MTDataTransferMode, either kDataTransferModeWifiOnly or kDataTransferMode3G; default is kDataTransferModeWifiOnly). It defines how the recorded data will be transmitted to the backend. With kDataTransferModeWifiOnly data will only be transmitted while the device has a Wifi connection. Settings the mode to kDataTransferMode3G will also allow the device to transmit data when only having a cellular connection.
  • kMTBatterySavingsMode (BOOL; default is true). If true MotionTag's battery saving tracking algorithm will be used. If set to false the SDK will fall back to a standard (always running in the background) CLLocationManager startUpdatingLocation routine with a desiredAccuracy of kCLLocationAccuracyKilometer.

Example:

private let settings: [String: AnyObject] = [kMTDataTransferMode: DataTransferMode.wifiAnd3G.rawValue as AnyObject,
                                             kMTBatterySavingsMode: true as AnyObject]
let motionTag = MotionTagCore.sharedInstance(withToken: TOKEN_OR_NIL, settings: settings, completion: {
                ...
            })
...         
motionTag.stop()

private let settings: [String: AnyObject] = [kMTDataTransferMode: DataTransferMode.wifiOnly.rawValue as AnyObject,
                                             kMTBatterySavingsMode: true as AnyObject]
motionTag.start(withToken: "A_VALID_TOKEN", settings: settings)

7. Callbacks

Optional

locationManager(_ locationManager: CLLocationManager, didChange status: CLAuthorizationStatus)

  • if the user changes the location authorization status of the app this callback will be called

didTrackLocation(_ location: CLLocation)

  • gets called whenever the SDK tracks a new location, also providing the timestamp of the last event transmitted.

didTransmitData(_ transmissionTimestamp: Date, lastEventTimestamp: Date)

  • gets called whenever the SDK has successfully transmitted a data package to the backend

8. Debugging

SDK

The SDK contains both the armv64 and the x86_64 symbols (which are necessary to run it on the simulator). When building a release version the cocoapods scripts will strip out all x86_64 symbols so that the release will be compatible with the App Store.

  pod 'MotionTagSDK', git: "https://gitlab.com/motiontag-dist/tracker-library-ios.git"