I found some interesting topics, such as : - How to get a photo's original filename in iOS? or : - Retrieving a filename for an ALAsset
but it says that you can read the local filename of the picture, but not the original name from the source image. Indeed, on ios, the pictures are renamed to :
/var/mobile/Media/DCIM/XXXAPPLE/IMG_XXXX.JPG ou .PNG
but when I sync my phone, itunes knows which pictures are already synced, so there must be a link between the original filename and the new ?