What will be their feed source?
We have free ranged a lot of chickens over the years, and we didn't supplement them with feed (for them). They cleaned up all the grain the horses, sheep, goats, cows and pigs spilled on the ground. They also scratched through the manure to get the undigested grains from these animals. They foraged for bugs and stuff, too.
Now the quantity of my chickens far exceeds the amount of wasted feed from the other animals, so anything that free ranges still has to have chicken feed available to them.
As far as being housed with the pigs, they will be your main predator to worry about. I've had only one hog that didn't kill chickens. I just lost a 6 month old Barred Rock roo to one of the hogs the other day. He didn't even see it coming. The hog just calmly walked by him and grabbed him. He was gone in a instant! I was standing 2 feet away and it happened so fast I couldn't even stop it. This rooster had lived around the hogs, and free ranged for several months. I also lost a grown Black Australorp roo to them. (There are a lot more losses, but these I know of in the last 2 weeks.) I've seen them wipe out an entire clutch of game chicks in an instant, when the hen took them into the hog pen to scratch for spilled feed.
I can't stop my free rangers from going into the hog pen, so I expect losses to them. I wouldn't purposely keep them together.
I know a lot of people thought "in the old days" farmers didn't feed their chickens. They did...just the way I described above, every day of the year. When the weather was bad enough to lock them into the coops, they fed them grains. They had a lot of losses to predators too.
I hope I have helped you from my experiences. I'm not saying it can't be done, I just can't do it here.
Jean