I know there have been tons of suggestions for iphone presence sensing, but I have a specific requirement...
I live in a condo, and I have the need to know when there is no one IN THE UNIT, so geofencing won't help. I use the iPhone Presence app which ironically works 100% with my Android phone, but my wife's iPhone has that nasty habit of turning off wifi when not being used -- I have found that I need to wait at least 28 MINUTES to determine that the phone is REALLY away!
My application? My wife has a habit of sometimes going out while something is cooking. Although she might just go to the pool, etc. she can get distracted by a friend and remain away longer than planned. I have a temperatures sensor in the stove hood, so I can tell if the stove is on -- as long as she is home, no problem. But I want to issue an alert if the stove is on and she is away for more than a few minutes. If there was some way of keeping the iphone wifi ON, that would help. Perhaps there are some other suggestions? BTW, I could be home and of no use because I might be engrossed in some work in my home office and not even know that the stove is on or that she went out... so motion sensors are probably not the best answer.
As long as she has her phone with her, get a homepod mini. They're presence detection is great. You can integrate that into hubitat.
I suggest re-thinking this automation.
Apparently you have some way of monitoring that the stove is on.
Can you use a motion zone to determine if the kitchen is unoccupied, and send a notification to both your phones if it remains unoccupied for 5 minutes if the stove is on?
In my townhouse, I used two motion sensors to create a pretty accurate motion zone in the kitchen.
We already have a always-on iPad running Homekit and integrated into Hubitat. Does it support iPhone presence as well? Sorry, I'm not very Apple-oriented
Motion sensors are tricky for us because we observe Jewish Sabbath and holidays, so they would need to be de-activated on those days.... doable I guess if they are USB-powered and connected to a smart plug, but seems overkill. Hoping for a simpler solution, but thanks!
Forgive my ignorance. Is the problem that the motion sensor is not allowed to be functional during the Sabbath? Or just that you can’t use the stove?
This is relatively easy to do. The Hubitat device for the sensor can be disabled on a schedule.
Both actually 
The stove, and all electric devices including cell phones are not used at all. Timer-activated lights, etc. are ok, so that's where my Hubitat comes in -- I have rules that adjust the thermostat base on time and outdoor temperature/humidity, lights based on times, etc.
If motion creates any sort of signal (even if ignored programmatically) that can be a problem. There are some exceptions, for example walking by a house that has a sensor-based security light that comes on -- since it is not your intention, it is not a problem. However, once you know it is there you would try to avoid it in the future (on Shabbos, of course)
My understanding of most of these devices is that they still generate the electrical signal, Hubitat just ignores it. That6s' why I don't use a NEST thermostat (always detecting, no way to turn off). I use the Honeywell smart thermostat
No you need a homepod/homepod mini or apple tv to act as a hub to do presence and geofencing
Or Apple TV.
Did you just edit your response, or did I read it wrong?
I edited lol
I think I've found a workable option for my particular case, sharing it just in case anyone finds it interesting....
Since the iPhone present sensor has the problem of thinking the phone is gone when Apple puts the Wi-Fi to sleep, I was finding that I had to wait up to 28 minutes before I could be sure it was really gone. In my case, when my wife is at home she sets her phone on a wireless charger in the kitchen. So I connected the wireless charger through a third reality plug, and tested the power draw when the phone is charging or not on the pad. I was able to determine a threshold that lets me know when the phone is not there. Since she always takes her phone with her when she leaves I use that in combination with the iPhone presence sensor. Now, when the presence sensor says the iPhone is not present, I pre-qualify it I also checking the status of the charger. If the phone is still on the charger I know it's a false reading and can ignore it. If the phone is also not there, then I simply wait about 5 minutes to see if the presence does not return... So far seems to work well, and has reduced the 28 minute wait to about a 5 minute wait.
Another similar option that might simplify it would be to create a Personal Automation in Shortcuts on the iPhone. I have mine set to Set Focus and Brightness when iPhone is connected to power, and another to set them back when disconnected.
is the wife still under warranty and do you still have the receipt?
Here is what I've used for my family the last few years without issue. It's rock solid, assuming you already have a working "home hub". You'll need to create 2 separate automations, one for when she arrives and one for when she leaves.
The "restocking fees" on that one tend to be a bit steep...
And don't forget the shipping charge.
