I believe this is a common issue and many answers don't work anymore, many just partial, if you are under iOS7 and your iPad app is Landscape only, but you want to use the UIImagePickerController with source UIImagePickerControllerSourceTypePhotoLibrary or UIImagePickerControllerSourceTypeCamera.
How to set it right, so it's working 100%? And you don't get mixed orientations and avoid the error "Supported orientations has no common orientation with the application, and shouldAutorotate returns YES".