So I'm retrieving an object that has a file as one of it's fields. In the Parse.com data browser the file is there and downloads. However, when I retrieve the object, PFFile *wordlistFile = [object objectForKey:kWSWordlistFilesFileKey]; is returning null, and so getDataInBackgroundWithBlock does nothing.
Here's the log of the object I'm retrieving. There is no reference to the file:
2013-12-03 12:07:10.635 WSPhoto[24958:a0b] object = <WordlistFiles:lRHFmHaPRg:(null)> {
ACL = "<PFACL: 0xd445670>";
language = Spanish;
}
And here's the full code. It appears I'm doing everything correctly based on some examples I've seen:
PFQuery* wordlistFilesQuery = [PFQuery queryWithClassName:kWSWordlistFilesClassKey];
[wordlistFilesQuery whereKey:kWSWordlistFilesLanguageKey equalTo:language];
[wordlistFilesQuery includeKey:kWSWordlistFilesFileKey];
[wordlistFilesQuery setCachePolicy:kPFCachePolicyNetworkOnly];
[wordlistFilesQuery getFirstObjectInBackgroundWithBlock:^(PFObject *object, NSError *error) {
if (!error) {
PFFile *wordlistFile = [object objectForKey:kWSWordlistFilesFileKey];
NSLog(#"******* wordlistFile = %#",wordlistFile);
// Show HUD view
AppDelegate *appDel = (AppDelegate *)[[UIApplication sharedApplication]delegate];
[appDel showGlobalProgressHUDWithTitle:#"Loading wordlist. This may take a while."];
[wordlistFile getDataInBackgroundWithBlock:^(NSData *data, NSError *error) {
if (!error) {
// Super private stuff here
}
// The data didn't load
else {
NSLog(#"loadWordlistFromDBByFile -- wordlist does not exist, loading by querying");
[self loadWordlistFromDBByQuery:language];
}
} progressBlock:^(int percentDone) {
}];
}
// The object didn't load
else {
NSLog(#"loadWordlistFromDBByFile -- wordlist does not exist, loading by querying");
[self loadWordlistFromDBByQuery:language];
}
}];
Make sure your kWSWordlistFilesFileKey is exactly the same as the name of the column seen on the data browser on Parse.com.
So if the column is called "wordlistfile", make sure:
kWSWordlistFilesFileKey = #"wordlistfile";
OK, this was a silly error. I reloaded the WordlistFiles class in the Parse.com Data Browser, and the file disappeared. Not sure how it happened. I swear to you guys I was staring it in the face. I re-uploaded and now it's retrieving, and there doesn't seem to be any weird behavior where it's deleting it.
Operator error.
Related
I'm trying to configure an Open Graph post. I've followed the code examples on the FB developer site, and, using a test_user, a post is supposedly successfully generated. Here is my code:
- (void)createOGObjectForImage:(NSURL *)imageURL
{
NSMutableDictionary<FBGraphObject> *object =
[FBGraphObject openGraphObjectForPostWithType:#"ogminigame:mini_game"
title:#"Mini Game"
image:#"https://fbstatic-a.akamaihd.net/images/devsite/attachment_blank.png"
url:imageURL
description:#""];
[FBRequestConnection startForPostWithGraphPath:#"me"
graphObject:object
completionHandler:^(FBRequestConnection *connection, id result, NSError *error) {
if(!error) {
NSLog(#"Result: %#", [result description]);
[self createOGActionWithResult:result];
} else {
NSLog(#"Error posting the Open Graph object to the Object API: %#", error);
[self sharePhotoWithShareDialog:self openGraphAction:nil];
}
}];
}
However, nothing is appearing on the test user wall. When I step through the code, I can see that when I create the OG object, the result has the following contents:
"FACEBOOK_NON_JSON_RESULT" = true;
More specifically, it looks like this:
So when I create my Action, when I try to retrieve the objectID using:
NSString *objectId = [result objectForKey:#"id"];
it obviously returns nil. Am I missing a stage with the result object? I've tried searching for similar problems but there doesn't seem to be much in the way of an explanation.
Well, it seems the code supplied on the Facebook developer site where you supply your custom stories is incorrect. Namely, it should look like:
- (void)createOGObjectForImage:(NSURL *)imageURL
{
NSMutableDictionary<FBOpenGraphObject> *object = [FBGraphObject openGraphObjectForPostWithType:#"ogminigame:mini_game"
title:#"Mini Game"
image:#"https://fbstatic-a.akamaihd.net/images/devsite/attachment_blank.png"
url:imageURL
description:#""];
[FBRequestConnection startForPostOpenGraphObject:object completionHandler:^(FBRequestConnection *connection, id result, NSError *error) {
if(!error) {
NSLog(#"Result: %#", [result description]);
[self createOGActionWithResult:result];
} else {
NSLog(#"Error posting the Open Graph object to the Object API: %#", error);
[self sharePhotoWithShareDialog:self openGraphAction:nil];
}
}];
}
So you cast the dictionary to an FBOpenGraphObject, rather than an FBGraphObject and call startForPostOpenGraphObject instead of startForPostWithGraphPath.
It seems to me Facebook need to be a bit more consistent with their documentation.
I still have nothing showing on the test_account page, but at least the above doesn't seem to be the cause of the issue...
My app creates an object (PFUSER) for each user, and an (PF) object for each event they participate in. This works fine. then i have two files associated with that event. i save the first file to a PFFile, then associate it to the event pfobject. when i use blocks and do this in the background, how can then make sure control continues to do the same for the second file?
I am new to blocks so maybe it would be clearer to me why its not working with callbacks, but it seems the block runs the save in another thread and the current one is abandoned before the next steps are taken.
Of course i'd like to do both of these as "save eventually" to allow offline use.
any guidance / examples you can point me to greatly appreciated.
thanks!
saveEventually doesn't support PFFiles yet; it needs a bit more smarts to handle resuming uploads between restarts. One trick that is already available, however, is that PFObject knows how to save its children, including PFFiles. You can just say:
PFUser *user = PFUser.currentUser;
user[#"icon"] = [PFFile fileWithData:iconData];
user[#"iconThumb"] = [PFFile fileWithData:iconThumbData];
[user saveInBackgroundWithBlock:^(BOOL succeeded, NSError *error) {
// user will automatically save its files & only call this once the
// entire operation succeeds.
}];
I'm not 100% what you mean because you didn't post any codes, but I'd imagine if you want to associate multiple PFFile to PFObject this is all you have to do:
PFObject *object = [PFQuery getObjectOfClass:#"MyFile" objectId:id];
[object addObject:profilePicture forKey:#"Photo"];
[object addObject:coverPicture forKey:#"PhotoCover"];
[object saveEventually];
From Parse's documentation it seems like saveEventually does what you want:
Saves this object to the server at some unspecified time in the
future, even if Parse is currently inaccessible. Use this when you may
not have a solid network connection, and don’t need to know when the
save completes. If there is some problem with the object such that it
can’t be saved, it will be silently discarded. If the save completes
successfully while the object is still in memory, then callback will
be called.
As currently neither saveEvetually nor saving to the local data store are supported, below is a category of PFObject I am using to at least save offline what can be saved or returning error:
- (void) dr_saveWithCompletionHandler: (void(^)(NSError* error)) completionBlock {
__block BOOL canSaveEventually = YES;
[[self allKeys] enumerateObjectsUsingBlock:^(NSString* key, NSUInteger idx, BOOL *stop) {
id object = self[key];
if ([object isKindOfClass:[PFFile class]]) {
PFFile* file = (PFFile*) object;
if (!file.url || file.isDirty) {
canSaveEventually = NO;
}
}
}];
void (^localCompletionHandler) (BOOL, NSError*) = ^(BOOL succeeded, NSError *error) {
if (succeeded) {
if (completionBlock) completionBlock(nil);
} else {
if (completionBlock) completionBlock(error);
}
};
if (canSaveEventually) {
[self saveEventually:localCompletionHandler];
} else {
[self saveInBackgroundWithBlock:localCompletionHandler];
}
}
I'm using what seems to be a simple invocation of the NSFileVersion class method removeOtherVersionsOfItemAtURL: inside a coordinated writing block for some iCloud conflict resolution.
When my devices go into 'spaz mode', which is a technical term for repeatedly opening and closing the application on a few devices, an EXC_BAD_ACCESS exception is thrown internally. Code snippet:
- (void)compareVersionChanges:(NSFileVersion *)version {
if (![DataLoader iCloudPreferenceEnabled]) {
NSLog(#"Ignoring iCloud changes (version comparison) based on user preference");
return;
}
NSLog(#"compareVersionChanges");
dispatch_queue_t aQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
dispatch_async(aQueue, ^(void) {
NSError *readError = nil;
NSFileCoordinator *coordinator = [[NSFileCoordinator alloc] initWithFilePresenter:(id)self];
[coordinator coordinateReadingItemAtURL:[version URL] options:0 error:&readError byAccessor:^(NSURL *newURL) {
DataContext *loadedContext = nil;
NSData *data = [NSData dataWithContentsOfURL:newURL];
NSError *e = nil;
loadedContext = [self convertXmlDataToContext:data error:&e];
if (e) {
NSLog(#"Done loading, error: %#", e);
[[DataLoader applicationDelegate] displayError:e];
loadedContext = nil;
}
if (!loadedContext) {
return;
}
id appDelegate = [DataLoader applicationDelegate];
DataContext *inMemoryContext = nil;
if (appDelegate != nil && [appDelegate respondsToSelector:#selector(context)]) {
inMemoryContext = [appDelegate performSelector:#selector(context)];
}
if (inMemoryContext) {
NSLog(#"Performing iCloud context synchronizating...");
DataContextSynchronizer *synchronizer = [[DataContextSynchronizer alloc] init];
ChangeSet *changes = [synchronizer compareLocalContext:inMemoryContext andRemoteContext:loadedContext];
if ([[changes changes] count] > 0) {
[SelectionManager disable];
#synchronized(appDelegate) {
NSLog(#"Applying synchronization changes...");
[synchronizer applyChangeSet:changes toDataContext:inMemoryContext];
NSLog(#"Synchronization changes applied");
}
[SelectionManager enable];
if ([appDelegate respondsToSelector:#selector(setSkipRefreshSave:)]) {
[appDelegate performSelector:#selector(setSkipRefreshSave:) withObject:[NSNumber numberWithBool:YES]];
}
dispatch_queue_t mainQueue = dispatch_get_main_queue();
dispatch_async(mainQueue, ^(void) {
[SelectionManager notifyListeners];
});
if ([appDelegate respondsToSelector:#selector(setSkipRefreshSave:)]) {
[appDelegate performSelector:#selector(setSkipRefreshSave:) withObject:[NSNumber numberWithBool:NO]];
}
[self save:[[DataLoader applicationDelegate] context]];
} else {
NSLog(#"No sync changes applicable.");
}
NSError *coordinateWriteRemoveError = nil;
[coordinator coordinateWritingItemAtURL:newURL options:NSFileCoordinatorWritingForDeleting error:&coordinateWriteRemoveError byAccessor:^(NSURL *theURL) {
theURL = [theURL copy];
NSError *removeOtherVersionsError = nil;
[NSFileVersion removeOtherVersionsOfItemAtURL:theURL error:&removeOtherVersionsError];
if (removeOtherVersionsError) {
NSLog(#"Error removing other versions: %#", removeOtherVersionsError);
}
}];
if (coordinateWriteRemoveError) {
NSLog(#"Error occurred coordinating write for deletion of other file versions: %#", coordinateWriteRemoveError);
}
}
}];
if (readError) {
NSLog(#"Done loading (outside block) error: %#", readError);
}
});
}
I thought a little syntax highlighting might make this easier to examine:
Link to image of code snippet and failure stack in Xcode
The error actually occurs on line 1404, and as you can see from the below screenshot, it's deep in Apple code territory.
Link to image of debugger
Before submitting a radar, I thought I'd check here to see if there's something I'm doing wrong? The extra [... copy] on line 1402 was just a quick check to make sure I'm not losing the reference to the block-provided argument, and will be removed.
Edit: An important note! I'm using ARC.
Edit 2: I've noticed that when calling:
[NSFileVersion otherVersionsOfItemAtURL:theURL]
The return value is nil, which indicates (via the documentation):
...or nil if there is no such file. The array does not contain the version object returned by the currentVersionOfItemAtURL: method.
So by checking the return value of this method before I make the call to removeOtherVersionsOfItemAtURL:, it has alleviated the issue. But I still find it strange that an EXC_BAD_ACCESS is thrown, rather than that method handling it properly.
I've noticed that when calling:
[NSFileVersion otherVersionsOfItemAtURL:theURL]
immediately prior to the call to removeOtherVersionsOfItemAtURL:, the return value is nil, which indicates (via the documentation):
Returns: An array of file version objects or nil if there is no such
file. The array does not contain the version object returned by the
currentVersionOfItemAtURL: method.
So by checking the return value of this method before I make the call to removeOtherVersionsOfItemAtURL:, it has alleviated the issue. But I still find it strange that an EXC_BAD_ACCESS is thrown by removeOtherVersionsOfItemAtURL:, rather than that method simply returning NO, or simply populating the provided NSError object.
I'll be filing a Radar and will update here when I hear back.
I'm creating an app with iCloud. But I have some problem. It creates directory on iCloud using NSFileWrapper, then it creates NSData (container) file in NSFileWrapper directory. I'm using this code to convert NSFileWrapper to NSMutableArray:
NSFileWrapper *MyWrapper=[[[MyDocument data] fileWrappers] objectForKey:#"myFile.doh"];
NSData *MyData=[NSData dataWithData:[MyWrapper regularFileContents]];
NSMutableArray *MyList=[NSPropertyListSerialization propertyListFromData:MyData mutabilityOption:NSPropertyListMutableContainers format:nil errorDescription:nil];
And it works correctly only on the device, which has created this container. On other devices the result of this code is BAD_ACCESS (in the second line of the code, where I start doing something with data). While debugging, function "regularFileContents" returns correct object with correct data size, but when I try to read this data, BAD_ACEESS(code=10) happens.
I'm using ARC, so it's not an error of memory management.
May be the problem is in some project/code sign settings? Any ideas?
Thanks!
I ran into this as well and after much experimentation I've found that even though the outer wrapper has downloaded the inner contents have not actually downloaded yet and that causes the call to regularFileContents to fail.
I've been calling startDownloadingUbiquitousItemAtURL on MyWrapper and once that completes the error is gone. Here's a method that checks the downloaded status of a file (assuming you know the url to your MyWrapper) and starts the download if it isn't downloaded yet.
-(BOOL)downloadFileIfNotAvailable:(NSURL*)fileURL
{
NSNumber *isInCloud = nil;
if ([fileURL getResourceValue:&isInCloud forKey:NSURLIsUbiquitousItemKey error:nil])
{
if ([isInCloud boolValue]) {
NSNumber *isDownloaded = nil;
if ([fileURL getResourceValue:&isDownloaded forKey:NSURLUbiquitousItemIsDownloadedKey error:nil])
{
if ([isDownloaded boolValue])
{
return YES;
}
NSError *error = nil;
[[NSFileManager defaultManager] startDownloadingUbiquitousItemAtURL:fileURL error:&error];
if (error)
{
NSLog(#"Download Failed :: %#", error);
}
return NO;
}
}
}
return YES;
}
I have an application that first loads some data into an UIManagedDocument, then executes saveToURL:forSaveOperation:completionHandler:. Inside the completionHandler block, it does an update of various elements of this database, and when it's done, it does another saving.
Besides that, the app has 3 buttons that reload the data, re-update the data, and delete one entity of the database, respectively. In every button method, the last instruction is a saving as well.
When I run all this in the simulator, all goes smoothly. But in the device doesn't. It constantly crashes. I have observed that, normally, it crashes when pressing the "delete" button, or when reloading or re-updating the database. And it's always in the saveToURL operation.
In my opinion, the problem comes when there are multiple threads saving the database. As the device executes the code slower, maybe multiple savings come at same time and the app can't handle them correctly. Also, sometimes the delete button doesn't delete the entity, and says that doesn't exist (when it does).
I'm totally puzzled with this, and all this saving operations must be done...In fact, if I remove them, the app behaves even more incoherently.
Any suggestions of what could I do to resolve this problem? Thank you very much!
[Edit] Here I post the problematic code. For first loading the data, I use a helper class, with this two methods in particular:
+ (void)loadDataIntoDatabase:(UIManagedDocument *)database
{
[database.managedObjectContext performBlock:^{
// Read from de plist file and fill the database
[database saveToURL:database.fileURL forSaveOperation:UIDocumentSaveForOverwriting completionHandler:^(BOOL success) {
[DataHelper completeDataOfDatabase:database];
}];
}
+ (void)completeDataOfDatabase:(UIManagedDocument *)database
{
[database.managedObjectContext performBlock:^{
// Read from another plist file and update some parameters of the already existent data (uses NSFetchRequest and works well)
// [database saveToURL:database.fileURL forSaveOperation:UIDocumentSaveForOverwriting completionHandler:nil];
[database updateChangeCount:UIDocumentChangeDone];
}];
}
And in the view, I have 3 action methods, like these:
- (IBAction)deleteButton {
[self.database.managedObjectContext performBlock:^{
NSManagedObject *results = ;// The item to delete
[self.database.managedObjectContext deleteObject:results];
// [self.database saveToURL:self.database.fileURL forSaveOperation:UIDocumentSaveForOverwriting completionHandler:NULL];
[self.database updateChangeCount:UIDocumentChangeDone];
}];
}
- (IBAction)reloadExtraDataButton {
[DataHelper loadDataIntoDatabase:self.database];
// [self.database saveToURL:self.database.fileURL forSaveOperation:UIDocumentSaveForOverwriting completionHandler:NULL];
[self.database updateChangeCount:UIDocumentChangeDone];
}
- (IBAction)refreshDataButton {
[DataHelper completeDataOfDatabase:self.database];
//[self.database saveToURL:self.database.fileURL forSaveOperation:UIDocumentSaveForOverwriting completionHandler:NULL];
[self.database updateChangeCount:UIDocumentChangeDone];
}
[Edit 2] More code: First of all, the initial view executes viewDidLoad this way:
- (void)viewDidLoad{
[super viewDidLoad];
self.database = [DataHelper openDatabaseAndUseBlock:^{
[self setupFetchedResultsController];
}];
}
This is what the setupFetchedResultsController method looks like:
- (void)setupFetchedResultsController
{
NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:#"Some entity name"];
request.sortDescriptors = [NSArray arrayWithObject:[NSSortDescriptor sortDescriptorWithKey:#"name" ascending:YES selector:#selector(localizedCaseInsensitiveCompare:)]];
self.fetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:request
managedObjectContext:self.database.managedObjectContext
sectionNameKeyPath:nil
cacheName:nil];
}
Each view of the app (it has tabs) has a different setupFetchedResultsController in order to show the different entities the database contains.
Now, in the helper class, this is the first class method that gets executed, via the viewDidLoad of each view:
+ (UIManagedDocument *)openDatabaseAndUseBlock:(completion_block_t)completionBlock
{
NSURL *url = [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject];
url = [url URLByAppendingPathComponent:#"Database"];
UIManagedDocument *database = [[UIManagedDocument alloc] initWithFileURL:url];
if (![[NSFileManager defaultManager] fileExistsAtPath:[database.fileURL path]]) {
[database saveToURL:database.fileURL forSaveOperation:UIDocumentSaveForCreating completionHandler:^(BOOL success) {
[self loadDataIntoDatabase:database];
completionBlock();
}];
} else if (database.documentState == UIDocumentStateClosed) {
// Existe, pero cerrado -> Abrir
[database openWithCompletionHandler:^(BOOL success) {
[self loadDataIntoDatabase:database];
completionBlock();
}];
} else if (database.documentState == UIDocumentStateNormal) {
[self loadDataIntoDatabase:database];
completionBlock();
}
return database;
}
You didn't really provide much code. The only real clue you gave was that you are using multiple threads.
UIManagedDocument has two ManagedObjectContexts (one specified for the main queue, and the other for a private queue), but they still must each only be accessed from within their own thread.
Thus, you must only use managedDocument.managedObjectContext from within the main thread. If you want to use it from another thread, you have to use either performBlock or performBlockAndWait. Similarly, you can never know you are running on the private thread for the parent context, so if you want to do something specifically to the parent, you must use performBlock*.
Finally, you really should not be calling saveToURL, except when you initially create the database. UIManagedDocument will auto-save (in its own time).
If you want to encourage it to save earlier, you can send it updateChangeCount: UIDocumentChangeDone to tell it that it has changes that need to be saved.
EDIT
You should only call saveToURL when you create the file for the very first time. With UIManagedDocument, there is no need to call it again (and it can actually cause some unintended issues).
Basically, when you create the document DO NOT set your iVar until the completion handler executes. Otherwise, you could be using a document in a partial state. In this case, use a helper, like this, in the completion handler.
- (void)_document:(UIManagedDocument*)doc canBeUsed:(BOOL)canBeUsed
{
dispatch_async(dispatch_get_main_queue(), ^{
if (canBeUsed) {
_document = doc;
// Now, the document is ready.
// Fire off a notification, or notify a delegate, and do whatever you
// want... you really should not use the document until it's ready, but
// as long as you leave it nil until it is ready any access will
// just correctly do nothing.
} else {
_document = nil;
// Do whatever you want if the document can not be used.
// Unfortunately, there is no way to get the actual error unless
// you subclass UIManagedDocument and override handleError
}
}];
}
And to initialize your document, something like...
- (id)initializeDocumentWithFileURL:(NSURL *)url
{
if (!url) {
url = [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject];
url = [url URLByAppendingPathComponent:#"Default_Project_Database"];
}
UIManagedDocument *doc = [[UIManagedDocument alloc] initWithFileURL:url];
if (![[NSFileManager defaultManager] fileExistsAtPath:[doc.fileURL path]]) {
// The file does not exist, so we need to create it at the proper URL
[doc saveToURL:doc.fileURL forSaveOperation:UIDocumentSaveForCreating completionHandler:^(BOOL success) {
[self _document:doc canBeUsed:success];
}];
} else if (doc.documentState == UIDocumentStateClosed) {
[doc openWithCompletionHandler:^(BOOL success) {
[self _document:doc canBeUsed:success];
}];
} else {
// You only need this if you allow a UIManagedDocument to be passed
// in to this object -- in which case the code above that initializes
// the <doc> variable will be conditional on what was passed...
BOOL success = doc.documentState == UIDocumentStateNormal;
[self _document:doc canBeUsed:success];
}
}
The "pattern" above is necessary to make sure you do not use the document until it is fully ready for use. Now, that piece of code should be the only time you call saveToURL.
Note that by definition, the document.managedObjectContext is of type NSMainQueueConcurrencyType. Thus, if you know your code is running on the main thread (like all your UI callbacks), you do not have to use performBlock.
However, if you are actually doing loads in the background, consider..
- (void)backgroundLoadDataIntoDocument:(UIManagedDocument*)document
{
NSManagedObjectContext *moc = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSPrivateQueueConcurrencyType];
moc.parentContext = document.managedObjectContext;
[moc performBlock:^{
// Do your loading in here, and shove everything into the local MOC.
// If you are loading a lot of stuff from the 'net (or elsewhere),
// consider doing it in strides, so you deliver objects to the document
// a little at a time instead of all at the end.
// When ready to save, call save on this MOC. It will shove the data up
// into the MOC of the document.
NSrror *error = nil;
if ([moc save:&error]) {
// Probably don't have to synchronize calling updateChangeCount, but I do it anyway...
[document.managedObjectContext performBlockAndWait:^{
[document updateChangeCount:UIDocumentChangeDone];
}];
} else {
// Handle error
}
}];
}
Instead of parenting your background MOC to the mainMOC, you can parent it to the parentContext. Loading and then saving into it will put the changes "above" the main MOC. The main MOC will see those changes the next time it does a fetch operation (note the properties of NSFetchRequest).
NOTE: Some people have reported (and it also appears as a note in Erica Sadun's book), that after the very first saveToURL, you need to close, then open to get everything working right.
EDIT
This is getting really long. If you had more points, I'd suggest a chat. Actually, we can't do it through SO, but we could do it via another medium. I'll try to be brief, but please go back and reread what I posted, and pay careful attention because your code is still violating several tenants.
First, in viewDidLoad(), you are directly assigning your document to the result of calling openDatabaseAndUseBlock. The document is not in a usable state at that time. You do not want the document accessible until the completion handlers fire, which will not happen before openDatabaseAndUseBlock() returns.
Second, only call saveToURL the very first time you create your database (inside openDatabaseAndUseBlock()). Do not use it anywhere else.
Third. Register with the notification center to receive all events (just log them). This will greatly assist your debugging, because you can see what's happening.
Fourth, subclass UIManagedDocument, and override the handleError, and see if it is being called... it's the only way you will see the exact NSError if/when it happens.
3/4 are mainly to help you debug, not necessary for your production code.
I have an appointment, so have to stop now. However, address those issues, and here's on