Application developers can subclass UIKit.UIDocument to create objects that are "Model-Controllers" and relate to Model (domain) objects analogously to how UIKit.UIViewController relate to UIKit.UIViews. iOS provides a number of functions, including background asynchronous reading and writing of application data, automatic and safe data-saving, storage that is automatically coordinated between the application sandbox and cloud services, etc.

At a minimum, application developers need to implement UIDocument.ContentsForType (for storage) and UIDocument.LoadFromContents (for retrieval). Additionally, application developers need to manage the lifecyle of the UIKit.UIDocument and this requires the application developer to set the preferred storage location, create a file URL, and discover, open, and close the file. Application developers should also track changes and resolve conflicts between document versions.

The members of this class can be used from a background thread.