I'm making an applications that let users take a photo and show them both in thumbnail and photo viewer. I have NSManagedObject class called photo and photo has a method that takes UIImage and converts it to PNG using UIImagePNGRepresentation() and saves it to filesystem. After this operation, resize the image to thumbnail size and save it. The problem here is UIImagePNGRepresentation() and conversion of image size seems to be really slow and I don't know if this is a right way to do it. Tell me if anyone know the best way to accomplish what I want to do. Thank you in advance.