To explain this in the way I understand, fibs are drawn from previous data, the previous run-up or drop. this is so you can gauge/estimate where the future price levels may be. so if the price of AAPL hit its peak and you want to know where the price will retrace, you draw the fib from the swing lowest point to the swing highest point. on a downtrend after completion and price starts to move up. do the opposite and draw from the swing highest point down to the swing low.