I collected a medium size swarm a week ago which issued from a local backyard hive. It was 10 m from its home hive on the trunk of a small apple tree 1m off the ground. I shook them into a cardboard box then had a beer with the owner as they all marched into their home. They were then transferred into a hive box with frames of foundation and a few full honey frames to give them food.
Generally a swarm queen is the old ex reigning hive queen who leaves the hive with a swarm so that her daughter queen will inherit the old home. So with a swarm you get a tired old queen who needs to be replaced by a young, virile and docile virgin queen from the queen bee breeder.
The old queen needs to be found and replaced by the new queen in a cage with her attendants. This cage has food and allows the hive and queen to become used to each other over a few days. The small cage has a time release door filled with sugar candy which the bees eat out and allow the prisoners entry into the hive. Hail the queen.
Within week or so the virgin queen will fly out alone once or twice to mate with as many drone bees as can keep up to the speeding queen. They all meet in a special area called drone congregation area high in the sky.
She will return to the hive and never leave again until her hive decides its time to swarm.