This function will move the instance running the code a set number of pixels in the specified direction until it meets an instance with solid flagged as true. You can use -1 or 0 for the maxdist being a default 1000px, ie: GameMaker Studio 2 will move the instance continually up 1000 pixels until it is out of collision.
move_contact_solid( dir, maxdist );
|dir||The direction to move in.|
|maxdist||The maximum distance the object can travel (-1 or 0 a default value of 1000 pixels).|
if !place_meeting(x, y + 1, obj_Floor)
The above code will check beneath the instance for a collision with "obj_Floor", and if there is none, then it will move it down until there is a collision, or 1000 pixels have been covered.