How can i wire a light fixture from a switch that is controlling a receptacle?

If you want the receptacles on full time and the new light switched now, you will need to bypass the switch to the outlets by wire nutting the wires together that were being switched , it will be 1 wire then really even though wire nutted. If you add a 3rd wire/ pigtail to that wire nutted connection you just used to bypass the switch, it can be sent to the switch and from the switch to the new ceiling fixture and will have to be ran new, running the new wires up into the attic through the firebreaks inside the walls between the walls studs from the switches location is the hardest part really,(my least favorite part!) you will also need to splice into the neutral leg to send with the hot leg for the new fixture as well or you are sending only 1 hot leg to the new light fixture and no return path to neutral, the opposite side of power from which you began being the hot leg at the switch.If neutrals not there at the switch, I would just run a new circuit with a new breaker , the better way to do it really! I wouldnt do it the way you suggest, especially if no neutrals available at the switch for you to use! To go through the hardest part of this job, being drilling then fishing the wiring up into the attic and not running a new circuit,(which is very easy) saves only the cost of a breaker and some romex, depending on how far from the breaker panel you are, is not the best route for numerous reasons. Say the outlets blow a breaker , your lights will also go out too! not the best thing to happen especially at night! I would simply run new romex with a new breaker and use a casablanca fan with light kit that will dim also! with the remote control! this way you don't have to drill and fish wiring through a wall of firebreaks and could just install a small junction box in a corner of the ceiling for the remote controls receiver/switch or servicing in the future, should receiver unit/switch ever go bad or troubleshooting fan in future. I engrave the purpose of the junction box on or inside the cover plate as well as dynamo label in the fans ceiling mounted base, just in case. As you can see I hate fishing wires through walls with firebreaks and wall plates etc!