The file URL with which the document was initialized.
- iOS 5.0+
The URL identifies the location of the document in the application sandbox. It includes the file extension, from which the file type is determined.
UIKit sets this property before it calls the completion handlers of the
revert(to. If, outside of these methods or their completion handlers, you want to wait for any pending file operations to complete before you access this property, you can call
perform and access the property value in the block parameter.