How do I verify a file's existence in iCloud?

Question

I know that the file exists, because I can download it, but I need to check to see whether it exists. I have tried using

[NSFileManager contentsOfDirectory         


        

Answer 1

Use a metadata query - here is some sample code

/*!  Creates and starts a metadata query for iCloud files

 */
- (void)createFileQuery {
    [_query stopQuery];

        if (_query) {
            [_query startQuery];
        }
        else {
            _query = [[NSMetadataQuery alloc] init];

            [_query setSearchScopes:[NSArray arrayWithObjects:NSMetadataQueryUbiquitousDocumentsScope, NSMetadataQueryUbiquitousDataScope, nil]];
            // NSString * str = [NSString stringWithFormat:@"*.%@",_fileExtension];
            NSString *str = @"*";
            [_query setPredicate:[NSPredicate predicateWithFormat:@"%K LIKE %@", NSMetadataItemFSNameKey, str]];

            NSNotificationCenter* notificationCenter = [NSNotificationCenter defaultCenter];
            [notificationCenter addObserver:self selector:@selector(fileListReceived) name:NSMetadataQueryDidFinishGatheringNotification object:_query];
            [notificationCenter addObserver:self selector:@selector(fileListReceived) name:NSMetadataQueryDidUpdateNotification object:_query];
            [_query startQuery];
        }

}

/*! Gets called by the metadata query any time files change.  We need to be able to flag files that
 we have created so as to not think it has been deleted from iCloud.

 */
- (void)fileListReceived {
    LOG(@"fileListReceived called.");

    NSArray* results = [[_query results] sortedArrayUsingComparator:^(NSMetadataItem* firstObject, NSMetadataItem* secondObject) {
        NSString* firstFileName = [firstObject valueForAttribute:NSMetadataItemFSNameKey];
        NSString* secondFileName = [secondObject valueForAttribute:NSMetadataItemFSNameKey];
        NSComparisonResult result = [firstFileName.pathExtension compare:secondFileName.pathExtension];
        return result == NSOrderedSame ? [firstFileName compare:secondFileName] : result;
    }];

    //FLOG(@" results of query are %@", results);
    for (NSMetadataItem* result in results) {
        NSURL* fileURL = [result valueForAttribute:NSMetadataItemURLKey];
        NSString* fileName = [result valueForAttribute:NSMetadataItemDisplayNameKey];
        NSNumber* percentDownloaded = [result valueForAttribute:NSMetadataUbiquitousItemPercentDownloadedKey];
        NSNumber *isDownloaded = nil;
        NSNumber *isDownloading = nil;
        NSError *er;
        [fileURL getResourceValue: &isDownloaded forKey:NSURLUbiquitousItemIsDownloadedKey error:&er];
        [fileURL getResourceValue: &isDownloading forKey:NSURLUbiquitousItemIsDownloadingKey error:&er];
        FLOG(@" Found file %@", fileName);
   }

}