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Silent push notifications allow us to remotely request a fresh location from a user. Radar supports requesting these locations through an API endpoint, starting with iOS and Android SDK version 3.24.0. There are two types of silent push notifications that can be sent to a device: regular app silent push and location service extension push. App silent push can be used to wake the app to perform a track if the app is in the foreground or background. This can be used to restart tracking if tracking was stopped due to device memory or CPU resource constraints. However the silent push notification will not work if the app has been manually killed by the user. Location extension service can be used to request a location for devices even if the app was manually terminated. The app will wake for ~30 seconds to respond to the request and perform a track request with a fresh location. The location extension service acts as a separate app, so it can only restart continuous tracking for 30 seconds before the extension is shutdown.

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Radar dashboard setup

Obtain an encryption key for APN (Apple push notification). Navigate to Settings tab, and enable push notifications. Then enter in the app’s bundle ID, team ID, key ID, and key for iOS. Enter the project ID, client email, and private key for Android. Then save the settings. Your private key should begin and end with -----BEGIN/END PRIVATE KEY-----, include this in your key.

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Build configuration

For iOS, Add the “Push Notifications” app capabilities, and turn on “Remote notifications” in the “Background Modes” capability. For Android, Add Firebase to your project and then generate a service account from the Firebase console. You’ll need the account details to send silent push notifications. Add the following firebase messaging service configuration to your project 
<manifest>
    ...
    <application>
        ...
        <service android:name="io.radar.sdk.RadarFirebaseMessagingService"
            android:exported="false">
            <intent-filter>
                <action android:name="com.google.firebase.MESSAGING_EVENT" />
            </intent-filter>
        </service>
    </application>
</manifest>
Add firebase messaging dependency to gradle 
dependencies {
    ...
    implementation platform('com.google.firebase:firebase-bom:34.5.0')
    implementation "com.google.firebase:firebase-messaging"
}

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App setup (automated setup)

Initialize Radar with RadarInitializeOptions.silentPush = true. 
import RadarSDK

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        // initialization Radar with the silent push option
        let radarInitializeOptions = RadarInitializeOptions()
        radarInitializeOptions.silentPush = true
        Radar.initialize(publishableKey: "prj_test_pk_...", options: radarInitializeOptions)

        return true
    }

}

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Manual setup

Initialize Radar, register for silent push notifications and pass the push token to Radar. 
import UIKit
import RadarSDK

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        // initialize Radar, silent push option defaults to false
        Radar.initialize(publishableKey: "prj_test_pk_...")

        application.registerForRemoteNotifications()

        return true
    }

    func application(_ application: UIApplication, didReceiveRemoteNotification userInfo: [AnyHashable : Any]) async -> UIBackgroundFetchResult {
        await Radar.didReceivePushNotificationPayload(userInfo)
        return .newData
    }
}

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Location extension service setup (iOS only)

Initialize radar, then set the app group. Start monitoring for location extension pushes from the main app. 
import UIKit
import RadarSDK

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    let locationManager = CLLocationManager()

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        let radarInitializeOptions = RadarInitializeOptions()
        radarInitializeOptions.silentPush = true // (or true if you only want location extension)
        Radar.initialize(publishableKey: "prj_test_pk_...", options: radarInitializeOptions)
        Radar.setAppGroup("group.yourApp.data")

        locationManager.startMonitoringLocationPushes() { data, error in
            Radar.setLocationExtensionToken(data?.map { String(format: "%02x", $0) }.joined())
        }

        return true
    }
}
When a location payload is received by the location service extension, pass the payload to Radar to handle the notification. 
import CoreLocation
import RadarSDK

class LocationPushService: NSObject, CLLocationPushServiceExtension {
    func didReceiveLocationPushPayload(_ payload: [String : Any], completion: @escaping () -> Void) {
        Radar.initialize(withAppGroup: "group.yourApp.data")
        Radar.didReceivePushNotificationPayload(payload, completionHandler: completion)
    }
}

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Usage

Silent push or location extension push notifications can be triggered by sending a POST API request to the /users/refresh endpoint. See the API reference for full details.

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iOS Environments

APNs operate in two separate environments for production and non-production app builds. When using the live Radar environment, Radar sends silent push notifications to the production APN environment, and when using the test Radar environment, Radar sends silent push notifications to the non-production environment. When using the live Radar environment, your device must be in a production build, and vice versa. You will receive “BadDeviceToken” if there is a mismatch.