UITable首先为UITableViewCell的最后一行加载UITableViewCell

While coding with UITableView, I encounter this bug that I couldn't understand. I got 3 rows for my table and setting 50px for each row, except the 2nd row that I set it 500px which fill the whole screen. Problem comes when I scroll down to bottom, my bottom role is repeating first row appearance.This is my custom code:While coding with UITableView, I encounter this