I am almost done developing an app. Right now I'm converting it to a universal app by supporting iPad to supported devices as well.
Can I set the app to use Landscape orientation only, since I am using UISplitViewController and want the Master View Controller to remain on the screen all the time? Is there any Apple policy that states that I cannot restrict it to Landscape only and I have to implement both portrait and landscape? Is there any chance my app can be rejected by setting it to Landscape only for iPad?
Don't worry, you'll be fine. Support both landscape orientations and neither portrait orientation if you want. I've got apps in the store that are like that.
However, note that UISplitViewController does have an option to keep both views on the screen all the time even in portrait. Use the delegate method splitViewController:shouldHideViewController:inOrientation:
to forbid hiding the master view:
So if your only reason for being landscape only is that you don't want to hide the master view, it is a false reason. Look, for example, at Apple's Settings app, which works like that; it is a split view controller that always shows both views in all four orientations.