What is the simplest way to play a video programmatically with Objective-C in Mac OS X 10.7 (Lion)? And if I want to support OS X 10.6 (Snow Leopard) too?
I noticed that iOS AV Foundation was introduced to OS X 10.7. Unfortunately the documentation seems to be written for iOS and I found it confusing.
"Simplest" depends on exactly what you're trying to do. If you want more control (e.g., rendering the movie as an OpenGL texture) or less (e.g., a completely independent window that you can just pop up and ignore), there might be different answers.
But for most use cases, if you want 10.6+ support, the simplest way to show a movie is QTKit. See the article "Using QTKit for Media Playback" in the Xcode documentation for a good starting point.