Multiplayer is the proper title thats what im trying to figure out
Proper title is "How to integrate game center into multiplayer"
What multiplayer? Your own custom made system, or the multiplayer plugin, or does game center run the multiplayer?
I don't know how game center operates.
Do they have some sort of api? Can they accept post/get etc etc
Can you write your own system to integrate with theirs?
Because there is no plugin, there is nothing available to do that... is it possible? (if they have a api etc - probably).
But unless you have the knowledge to do this, then NO!, and I presume, if you had the knowledge you wouldn't be asking this question...
Understand... this would be a pretty big job, and nobody is going to do it for free.
I have no idea how game center works - but I would imagine this would require some very specilized skills, modifications...
So "How to integrate game center into multiplayer"
You pay someone... but the chances are very slim that you yourself can infact do this...(I am speaking from a point of view that I don't know how game center integrates games into their system)
If you can write your own plugins, have no problem with sending/retrieveing info and interacting with api, then this is very doable.
Lets Face Facts!
Lets be honest, you have posted a bunch of How to I.... so you obviously are in over your head.
You need to spend at least a year learning the tool "Construct2" and you will need to learn a vast amount to handle anything that is multiplayer, especially if you want to tie it into game center, and play with the big boys. Your skill level is not anywhere it needs to be.
Your time would be best suited doing a lot of small things, learning as you go... or raise a huge amount of capital (because this is going to cost you lots)