Novice help - UITableview not a cell in the last question to add a label

In the last line of the cell to add a label, cell's style is UITableViewCellStyleSubtitle; willDisplayCell in the delegate method to label did specify the size and coordinates; cellForRowAtIndexPath colleagues specifies the size and coordinates of the label, and after checking the label if it exists it will label removed from the cell, and then create; content label can be displayed correctly, but after sliding screen lable if the position is not right, I do not know why, please enlighten heroes, thank you.
Reply:
cell.addsubview: label
Well this just fine