It looks like Facebook finally gave in with allowing embeds of posts and photo’s in native iOS-apps.
A few months ago, it wasn’t possible anymore to embed these kind of content in a app, without using a mediator in the form of a webpage. This caused the need to create a dynamic webpage of which contained the actual embed. At that point you embedded the dynamic page instead of the actual post. But now it’s not necessary anymore.
In the first test, that I ran in Apple Xcode, I see the post rendered as it should be.
Facebook did admit the blocking of non-browsers on iOS, but they never told why. My only guess: when they don’t know on what platform they are embedded, they can’t use the data for themselves or advertisers.