Hi,
the relation between your swipe and the force direction and magnitude is always requiring tweaks because the force is added in a 3d world, not in 2d.
so, to do this, you need the following:
-- the direction of the force. Is it related to the swipe direction? and how does that translate into your 3d world? are you implementing a 2d game or is it really a 3d game?
-- as for the magnitude of the forec, you will always need to have a multiplier, so get the magnitude of the swipe, apply your multiplier and then multiply the value to the direction vector defined above, this will be your final vector to inject in Add Force.
now, to get a direction based on a gameobject ( say you want to push a gameobject always from behind itself), use the action "Transform Direction" and define the local axis ( for example 0,0,1 will be the forward direction)
Could you explain what you are after in the end? I might have already a sample that match your needs for you to study.
bye,
Jean