Hi,
I have over 25 years experience in programming with more than 15 years in web development and quite some years with mobile apps.
As far as I understand an IoT gateway iOS app developed. I have already worked quite much in the filed of IoT (MQTT, OPCUA, ...) and so can implement your ideas fast & reasonably priced.
Please provide me with more details or documents - if you have. So we can talk about the specific functions you need.
I follow the "agile development" approach - meaning, that through the entire process I update you with new versions, as soon as it has some major changes / new functions. You can than check the progress and we can talk about how you like it and what has to be changed.
I would start with a MockUp - setting up the user interface for the app, every button, ... will be there but with dummy data and clicking buttons will not do anything (in most cases).
Then I will make this app alive by adding functionality.
You can find some of my previous work in my portfolio here on freelancer.com
If you have any questions - just ask.
I will be happy to hear from you soon.
Best regards,
Fabian