I'm trying to create some application that connects to blue tooth devices. A simple thing like a bluetooth barcode scanner that scans and sends a number to my app. I want to know which framework or something to be used in my app that can integrate the barcode scanner with my app. Is there any API or examples or tutorials etc that can help me implement such things?
Apple provides an API called the External Accessory framework, which can be used to interact with paired Bluetooth devices or devices connected through wired, Apple Connector at the base of the device.
However, to be able to use a paired device from within your application as you desire, you will have to a device that is designed to be compatible with iOS devices (meaning, the manufacturer must be a member of the Apple MFi program) and the device manufacturer must provide a protocol that you must add to your applications info.plist file.
If you have bought an off-the-shelf, Bluetooth barcode reader, there is a fair chance that you can not do what you are trying to do. If the device states that it can be integrated into custom iOS applications, consult the device manufacturer for further support regarding setting up your application to interact with their hardware.