import PWCore

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey : Any]? = nil) -> Bool {
    // These values can be found for your application in the MaaS portal at http://maas.phunware.com/clients.    
    PWCore.setApplicationID("APPLICATION_ID",
                            accessKey: "ACCESS_KEY",
                            signatureKey: "SIGNATURE_KEY")

    ...
}

switch PWCore.isAdvertisingIdentifierPermissionRequestable {
case .allowed:
    PWCore.requestAdvertisingIdentifierPermission { (advertisingIdentifier) in
        // Advertising identifier available
        print("Advertising Identifier: \(advertisingIdentifier)")
    } failure: { (error) in
        // Advertising identifier not available
        print(error)
    }
case .notAllowed:
    // Authorization is either restricted or has been previously denied
    print("Advertising identifier cannot be requested.")
case .alreadyAuthorized:
    // Advertising identifier is already available
    print("Advertising Identifier: \(PWCore.deviceID())")
}