I tried using a couple of IOS libraries such as MQTT-Client-Framework and MQTTKit to access the Arduino MQTT server but i could not connect to it. These libraries works well with non SSL MQTT servers.I tried bundling gdroot-g2.crt file from godaddy too with no success. Has anybody successfully connected to the server? If so, can you please give me some direction on how to achieve this?
You can connect to Arduino Cloud just if you are authenticated and using https connection.
are you using the device_ID and device_psw you get from the cloud platform to connect to Arduino Cloud from IoS?
give a chance to the paho library.
Hi lorenzoromagnoli,
Thanks for your comments and the reference link. I managed to get connected! 
Hi All,
I am iOS APP developer. I am getting error while connecting with MQTT host because of SSL.
This is the Error.
Do i need to convert .crt file in der or cer format
[MQTTSession] mqttTransport didFailWithError Error Domain=kCFErrorDomainCFNetwork Code=1 "(null)"
I've have some major successes in working with Arduino and Raspberry .. after a long and bloody battle with both devices .. there are two good postings homeautomationforgeeks.com good tutorials on working with OpenHAB and Arduino ...As well as google makeuseof OpenHAB ..
I've found using a Mqtt tool like Mqttool is a good way to actually see what's being posted .. I'll upload a working DHT/Mqtt sketch later today ..if you still need some help