Is there any way to upload an image (UIImage) directly from an iPhone app to a user's wall/feed?
All the samples I see are either using a json-embedded link or they use the photos.upload call with album ID (aid) which results in the user getting the image in his photo album(s).
What I want to do is to upload an (UI)Image created (by the user) inside an iPhone app and upload to his/her wall. Is this possible? Sample code would be highly appreciated.
This isn't possible. To understand why, you have to consider the conceptual model that Facebook currently uses: Posts on a user's wall are just bits of text optionally attached to some link URL. That link URL can be some random image on the web, or it can just as well be an image that the user already has in their photo albums.
But a wall post cannot inherently "contain" an image in and of itself. Therefore you need to host the image somewhere, be it on your own site, or on Facebook itself, inside one of the user's albums by uploading it first to there.
I'm trying to figure out the same thing myself. One thing I did find out is that if you post the "Wall Photos" album they do get posted to the wall. However you only have a wall photos album if you've uploaded photos to your wall from your profile page before. And even then, you need to get the album aid and then post to it.
EDIT
Found a much better solution. First upload the photo to your default album, then make a post to the wall with the link to your photo that was returned when uploading (not a link to the image but the page the image is on).