awsiot-5.js

func registerSubscriptions() {
        func messageReceived(payload: Data) {
            let payloadDictionary = jsonDataToDict(jsonData: payload)
            print("Message received: \(payloadDictionary)")
            
            // Handle message event here...
        }
        
        let topicArray = ["topicOne", "topicTwo", "topicThree"]
        let dataManager = AWSIoTDataManager(forKey: "kDataManager")
        
        for topic in topicArray {
            print("Registering subscription to => \(topic)")
            dataManager.subscribe(toTopic: topic,
                                  qoS: .messageDeliveryAttemptedAtLeastOnce,  // Set according to use case
                                  messageCallback: messageReceived)
        }
}

func jsonDataToDict(jsonData: Data?) -> Dictionary <String, Any> {
        // Converts data to dictionary or nil if error
        do {
            let jsonDict = try JSONSerialization.jsonObject(with: jsonData!, options: [])
            let convertedDict = jsonDict as! [String: Any]
            return convertedDict
        } catch {
            // Couldn't get JSON
            print(error.localizedDescription)
            return [:]
        }
}