ai to swf conversion represents export of Adobe Illustrator content to Adobe Flash, or using .ai elements for preparing new .swf files. Flash has been discontinued some years ago now, but you can still find various Flash tools that can be used for this purpose.
Old versions of Adobe Illustrator could do this directly, before the support for the format has been dropped, so finding old versions of the tool might be actually one of the options how to convert ai to swf. But so is using various utilities and Flash tools.