iPhone 3.5mm Audio jack specification (buttons) I have done some research in regards to this but I seem to get conflicting requirements.

So Android defines and have published a specification for this.
https://source.android.com/devices/accessories/headset/plug-headset-spec.html

Apple on the other hand, I am unable to find out if they publish this information.
I have also found out that some Android headset (3 button) does not seem to be compatible with iPhones. 

Does anybody know what methods Apple iPhone devices use for 3 button detection?
Is there somewhere a publish specification released?
Apple will give you the information to work with/duplicate the "Headset Remote and Mic" (aka the little box on each pair of EarPods that have the three buttons and microphone) if you join their MFi program, as noted in the MFi FAQ and on BoingBong when the three-button setup first came out. I haven't seen anyone online reverse-engineer it and publish information about how it works.