I am using this code for posting image, but don't get image ID in response.
FBSDKSharePhoto *photo = [[FBSDKSharePhoto alloc] init];
photo.image = self.image.image;
photo.userGenerated = YES;
FBSDKSharePhotoContent *content = [[FBSDKSharePhotoContent alloc] init];
content.photos = @[photo];
[FBSDKShareDialog showFromViewController:self
withContent:content
delegate:self];