Make a simple iphone app that can connect another bluetooth device
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I know some basic about iOS programming, now i want to connect my app to another non iphone device e.g. connecting to a bluetooth device that can control a light bulb on and off, or control any furnitures. 

My question is, besides iOS xcode, what kind of program i need to learn in order to achieve my goal? 

Is there any sources that i can learn from it? 

Many Thanks. 