I'm sharing an image, along with a url and some text, with a `UIActivityViewController`. Everything works great, except the image file name is always 'Image-1' with no extension. In some cases this causes a big problem, such as in the mail app which won't open an image without an extension at all.

The image is being generated by the application and exists as a `UIImage`.

Is there a way to control the file name and add the correct extension to the image?