Hey guys, we're working on an Engineering university project and was wondering if we could get feedback or advice from the community here. We're trying to notify someone (an admin) using an iPhone (through an app) if a person has passed through a boiler room of a building, and whether they are near the door or not. The usual person who is walking past the door would have a smartphone. We initially thought about putting RFID tags on the doors which would sense the smartphone the person is carrying, as they walk past the door. This would show up on the app (that the admin is using) as "someone is near the boiler room door" and once they leave a specific field then it would show up on the app as "nobody is near the boiler room door". Hope I made sense. Now unfortunately we realized that the iPhone does not have any RFID capabilities, and we want to allow the admin to use the basic iPhone hardware (the admin is not buying external RFID readers). All major Android phones have NFC technology, so they should have RFID capabilities. But we want the admin to be able to use any phone (specifically the iPhone). Is there any alternative to RFID we could use? We were thinking of having motion or weight sensors on the doors to detect whether someone has passed it or near it (some doors are very close to each other, would it still work?) and having it send out a simple boolean "T or F" to a cloud system if it senses someone. The iPhone would then pull the information from the cloud and onto the app, allowing the admin to see it in real time. Is this possible? How difficult would this be? How expensive would such sensors that, when triggered, they push a boolean to the cloud be? How would the app pull the data from the cloud? Basically the end user should be able to see the status of the boiler room door area through their basic smartphone hardware (including iPhone). Any feedback would be appreciated.