Fix memory leak in demo project.
Fix memory leak in demo project.

siuying/FPPopover,Empora/FPPopover,uken/FPPopover,mjasa/FPPopover,zuojx1013/FPPopover,johnlinvc/FPPopover,Empora/FPPopover,zuojx1013/FPPopover,mjasa/FPPopover,alvises/FPPopover,adozenlines/FPPopover,alvises/FPPopover,adozenlines/FPPopover,TechSmith/FPPopover,TechSmith/FPPopover,siuying/FPPopover,uken/FPPopover,Oblong/FPPopover