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How do you detect when a file is changed in iCloud?

When a file is changed in iCloud (whether added, deleted, or the content changed), I would like to call a method I created ([self methodName]) so that I can update my table view with the names of the new files. How am I notified of the file change? Do I need to listen for a NSNotification (if so, what is it?) or do I have to check manually? Thanks.

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Jack Humphries Avatar asked Jul 02 '12 02:07

Jack Humphries


2 Answers

The name of the NSNotification I have to listen for is NSMetadataQueryDidUpdateNotification. This is how I did it:

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(queryDidUpdate:) name:NSMetadataQueryDidUpdateNotification object:query];

...

-(void)queryDidUpdate:(NSNotification *)notification {

    //something changed, reload (NSMetadataQuery, create NSPredicate, rerun the query, etc.)

}
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Jack Humphries Avatar answered Sep 20 '22 14:09

Jack Humphries


This section of the Apple developer website contains a great tutorial for setting up document-based iCloud apps.

To answer your questions, though: as long as your document is a UIDocument you can register for a notification. Just search that page for "Monitoring Document-State Changes and Handling Errors" - there is tons of source code to help you out.

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Aaron Brager Avatar answered Sep 18 '22 14:09

Aaron Brager