Google Cloud IoT : How to connect to MQTT bridge from iOS applications written in Swift?

Question

I couldn't find any documents on how to connect to Google Cloud IoT MQTT bridge from Swift-based applications. Is it possible to connect? Any references or links or samples would be appreciated.

Answer 1

Edited answer responding to comment: To connect using the MQTT bridge to IoT Core, check out the code here.

We don't have an IOS/Swift code example there, but you should be able to see the various pieces you need from the Node or Python examples. The URL/endpoint for IoT Core is mqtt.googleapis.com:8883. The MQTT client's user/pass is going to be blank for the user (unused) and the encoded JWT for the password. The same code has what it looks like, and should be enough to get you started hopefully.

To communicate with IoT Core, the MQTT topics are devices/<device_id>/events/ for telemetry from device to Cloud, and if you want to report state of the device to be stored by IoT Core, it's devices/<device_id>/state/ and if you want to send messages from IoT Core back down to the device, it's either devices/<device_id>/config/ for persistent messages that will be delivered on connect if the device isn't actively connected, or devices/<device_id>/command/ if it's more of a fire and forget, lower latency type message.

Original answer: We don't have any documentation around this particular use case yet, but I found this:

https://github.com/emqtt/CocoaMQTT

Which enables MQTT client connections from IOS and is written in Swift, so that should work. In addition to this, you'll need a library to encode a JWT (Json Web Token) for the auth side of things.

Having said that, you could ditch MQTT entirely and just use the HTTP bridge in IoT Core, as that might be easier? You can see the docs for doing that here: https://cloud.google.com/iot/docs/how-tos/http-bridge. You'll still need the JWT piece for the auth, but it would keep you from having to implement MQTT in the app.