How to preserve EXIF data when saving images to Photos library?

I've noticed that iOS seems to strip all meta data of the photo when it is being downloaded or uploaded. I've confirmed that this is only an issue on iOS, uploading/saving image with Dropbox and its meta data remains intact.

Ironically, seems like photos in iOS has its meta data natively embedded to every photo to arrange/order the photos. Why does iOS need to cause inconvenient to users by stripping those information during transmission? (Correct me if I'm wrong; try testing this out yourself 😉)