My boar, Marley, will very happily sit in the cage and let me and my OH put our hands over and stroke him. He is a rescue and we got him when he was about 4-5 months old we think, and I have had him since September. He was letting us stroke him before Xmas but before that we just used to sit and hand feed veggies to them all. I think he is just an extra special tame pigster x)
Out of the two girls, one is very confident and isn't at all scared of you. She won't scamper at a loud noise or if I make a sudden noise, however she will not tolerate being stroked and will dance around your hand to avoid it. I think this may be because before I had her she had a severe case of ringworm, so I suspect her skin is more sensitive/she has bad memories of people touching her and it being painful.
The other girl is very skittish, and doesn't seem to be improving much. I've had her since October - she was very young when I got her too and has grown up around me but still is very scared and will run at any movement.
I think it depends on the personality of the pigs. Obviously hand feeding really does help - but Mabel my really skittish girl isn't even at the stage where she will take food from me yet, after over 6 months. Molly and Marley would take food straight-away and are confident around humans.