Update the comments and remove the unnecessary main queue check
Update the comments and remove the unnecessary main queue check

dreampiggy/SDWebImage,awkward/SDWebImage,smule/SDWebImage,awkward/SDWebImage,dreampiggy/SDWebImage,awkward/SDWebImage,tualatrix/SDWebImage,zhang-yawei/SDWebImage,Insfgg99x/SDWebImage,rs/SDWebImage,dreampiggy/SDWebImage,iheartradio/SDWebImage