Don't have to invert UITableview

[peiweichen]

UITableview shrink if add last row because when inputBar's height changes if text input exceed 1 rows which also changes tableview's height constraint,which cause tableview's shrink horrible user experience.I recommend make tableview's bottom constraint relative to view and offset should be (keyboard height+input bar's initial height) ,not (keyboard height+input bar's appropriate height,)