Override this method to load the document data into the app’s data model.
- iOS 5.0+
If you cannot load the document data for any reason, return by indirection an
NSErrorobject that encapsulates the reasons you can’t. Otherwise, ignore this parameter.
Override this method to accept and load the data for a document. After
UIDocument reads the document data from the file located at
file it calls your subclass, passing the data to the subclass in this method. This method is called on the queue that the
open(completion method was called on (typically, the main queue).