fix selection removed when index path nil
fix selection removed when index path nil

OceanLabs/DLFPhotosPicker,OceanLabs/DLFPhotosPicker,nicnocquee/DLFPhotosPicker,dawangjiaowolaixunshan/DLFPhotosPicker,nicnocquee/DLFPhotosPicker,nicnocquee/DLFPhotosPicker,dawangjiaowolaixunshan/DLFPhotosPicker