Saving video files to iCloud - core-data

Question

I am currently trying to save video files to iCloud. I am using Core Data to save filename strings (filename.MOV) for each video, to then retrieve them from the ubiquity container. It all works locally (files save, and can be accessed from their URLs), but I am struggling to obtain the videos over iCloud. The Core Data syncs, so I have access to the file names, but when I try to obtain the video from the URL, I am unable to.
This is how I save the video after obtaining its url (videoURL below) from UIImagePicker, and creating a unique string from the current date:
NSString *videoFileName = [stringFromDate stringByAppendingPathExtension:#"MOV"];
NSURL *ubiquityContainer = [[NSFileManager defaultManager] URLForUbiquityContainerIdentifier:nil];
NSURL *saveToURL = [ubiquityContainer URLByAppendingPathComponent:videoFileName];
BOOL ok;
ok = [[NSFileManager defaultManager] setUbiquitous:YES itemAtURL:videoURL destinationURL:saveToURL error:nil];
if (!ok) NSLog(#"error saving");
I then have a Core Data table view to list all of the videos. Here I observe changes in the Core Data to sync with iCloud and reload (this all still works fine):
- (void)viewDidLoad {
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(reloadFetchedResults:)
name:#"SomethingChanged"
object:[[UIApplication sharedApplication] delegate]];
}
- (void)reloadFetchedResults:(NSNotification*)note {
[self performFetch];
}
At this point, I want the ubiquity container to update, so that when I choose a video, and segue to a view controller to watch it, the video file can be found. (self.video is my Core Data video entity) (asset is is the video asset, which I can play back)
NSURL *ubiquityContainer = [[NSFileManager defaultManager] URLForUbiquityContainerIdentifier:nil];
ubiquityContainer = [ubiquityContainer URLByAppendingPathComponent:self.video.url];
AVURLAsset *asset = [AVURLAsset URLAssetWithURL:ubiquityContainer options:[NSDictionary dictionaryWithObject:[NSNumber numberWithBool:YES] forKey:AVURLAssetPreferPreciseDurationAndTimingKey]];
AVAssetTrack *videoTrack = [[asset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0];
This is where I run in to trouble. On the device where I took the video it works, but on another device, no file is found (objectAtIndex:0 is beyond bounds).
This is the metadata query I call at view did load:
NSMetadataQuery * query = [[NSMetadataQuery alloc] init];
NSString * filePattern = [NSString stringWithFormat:#"%#", self.video.url];
[query setPredicate:[NSPredicate predicateWithFormat:#"%K LIKE %#",
NSMetadataItemFSNameKey, filePattern]];
[query startQuery];
My metadata query may be at fault, or there may be more issues. Any help would be greatly appreciated!

Answer 1

I assume you are on iOS, which means on your second device the media file hasn't been downloaded (iOS doesn't download iCloud files until you actually access them, OS X downloads everything - see the docs).
To ensure the file is on the device use startDownloadingUbiquitousItemAtURL:error: or coordinateReadingItemAtURL:options:error:byAccessor: if you want to know when it's done (in the Accessor block). You will need to call the later anyway to do your coordinated read, so the first method has limited usefulness.