Ok, this is probably a pretty stupid idea, but ....
I read that wild pigs are pretty smart. So, lay out mouse traps around the yard at night so when they get close they snap shut and startle them. If it snaps over their foot (hoof?) it probably would sting a bit and maybe make them head to greener pastures? Or annoy the heck out of the neighbors and lie in wait for them at night and throw firecrackers at them like you do to make sure geese don’t nest in your back yard.
Course, you can also hire a trapper:
http://animaltrappersinorlando.com/hog/
???
Just some ideas.