iPhone presence detection

[admin]

That shell solution assumes that your iOS device has a fixed IP, you can do in Lua like this. I cannot guarantee that this code will work, you have to try and debug it yourself

Code:

function checkiosdev(ip)
  local sock, res

  sock = require('socket').udp()
  for i = 1, 10 do
    sock:sendto('123', ip, 5353)
    os.sleep(1)
  end

  res = os.execute('ping -c 2 -W 10 ' .. ip)
  return res == 0
end

seen = checkiosdev('192.168.1.10')
grp.update('1/1/1', seen)

When phone/tablet is locked (in sleep state) sending UDP packets to port 5353 causes it to wake for a short period. During that period device can be pinged to check if it's in the network or not.