does anyone know of any code violations to use nm cable to connect/interconnect smoke detectors and other related devices . should all wiring be a type (ci) cable with fire resistant ability ?In my area most of the electricians use nm cable to connect smoke detectors.

You don't say what type of occupancy this will be in. Three wire w/g NM-B is commonly used in a residential setting unless prohibited by local amendments.

As Jim said, what type of system is this? Line voltage smoke detectors or a power limited fire alarm system?

Requirements for both of these systems, especially fire alarms, vary drastically from state to state, so your best bet is to check your local and/or state codes.

Peter