Making an iphone connect to something external

right, pretty weird question and i litterally know nothing about iphone development apart from a very small bit.

I basicly want to try and create an app which when pressing a button on screen, somehow connects to a receiver, and when pressing it causes this receiver to make a certain noise.

Is there anyway of doing this sort of thing?

How would i get it to connect?

what sort of connection? etc?

Might be a ridiclous idea, but just wanted to see if its possible and if it is, how to do it?

Thanks to anyone who may be able to help out with this.

You can connect wirelessly via WiFi and BlueTooth. BT is limited though in that Apple has made it so you can't connect to non-authorized gadgets. Apple also has a way for developers to apply for connected device capability via the port. That requires approval. Another option I've seen is people writing apps that use the speaker as an output medium.