I first fed swallows a few years back,it takes a while but they get it in the end . Crumble dried mealworms add water to make a sloppy gruel in a shallow dish,easy bit done. I first put dish on floor but soon realised too vulnerable and not in line of flight.
Find somewhere in the flightpath near a favoured entry/exit point.mine is on the top of an old dresser by the end door of the steading,keep it wet ,best placed/checked when they aren’t looking/asleep .It may take awhile for them to get used to something new leaving some handy nest building material (tumble dryer fluff) can help too.
Leave them to it,in the cold it will last 4/5 days before it needs changing any left goes to the blackbirds at the other end of the steading , try not to let them see where it’s come from,honest it they find the dish it will get mobbed.
At one time we had an insec o cutor light that attracted insects that was popular those that didn’t get zapped got caught ant the fried ones tipped out on a plate.
Give it a try they do learn eventually