I am trying to develop a feature for my app which can measure the room temperature & depending upon the results it will act/respond accordingly...
Does iPhone have built-in temperature sensor that can be used for measuring room temperature ??
None of Apple's mobile devices have that ability.
Your app would need to talk to a HomeKit enabled device in the room instead, I think.
If this is something you'd like to see in the future, feel free to make a feature request via theReport Bugs link.
Good luck.