How to open/create UIManagedDocument synchronously?

How do I create a global UIManagedDocument instance per document-on-disk shared by my whole application using blocks?

• I am trying to design a helper method which will retrieve a UIManagedDocument, then open and return it, so that I may access the same UIManagedDocument from several places in my app. I am having trouble with the asynchronous nature of this as I am not too familiar with blocks. Ideally the sequence of events would be this: Class X calls the helper method to retrieve the UIManagedDocument and includes a block of code to run when the opened document is returned. The class method retrieves the UIManagedDocument and calls openWithCompletionHandler or saveToURL as necessary, and includes a block of code to run when the opened document is returned. openwithCompletionHandler or saveToURL complete their task, and return with success = YES and run the code in its block The class method completes its task and returns with an open UIManagedDocument and runs the code in its block Can I pass the original block through somehow? Here's my code so far. Any thoughts hugely appreciated, thanks. // This is a dictionary where the keys are "Vacations" and the objects are URLs to UIManagedDocuments static NSMutableDictionary *managedDocumentDictionary = nil; // This typedef has been defined in .h file: // typedef void (^completion_block_t)(UIManagedDocument *vacation); // The idea is that this class method will run the block when its UIManagedObject has opened @implementation MyVacationsHelper + (void)openVacation:(NSString *)vacationName usingBlock:(completion_block_t)completionBlock { // Try to retrieve the relevant UIManagedDocument from managedDocumentDictionary UIManagedDocument *doc = [managedDocumentDictionary objectForKey:vacationName]; // Get URL for this vacation -> "<Documents Directory>/<vacationName>" NSURL *url = [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject]; url = [url URLByAppendingPathComponent:vacationName]; // If UIManagedObject was not retrieved, create it if (!doc) { // Create UIManagedDocument with this URL doc = [[UIManagedDocument alloc] initWithFileURL:url]; // Add to managedDocumentDictionary [managedDocumentDictionary setObject:doc forKey:vacationName]; } // If document exists on disk... if ([[NSFileManager defaultManager] fileExistsAtPath:[url path]]) { [doc openWithCompletionHandler:^(BOOL success) { // Can I call the completionBlock from above in here? // How do I pass back the opened UIDocument }]; } else { [doc saveToURL:url forSaveOperation:UIDocumentSaveForCreating completionHandler:^(BOOL success) { // As per comments above }]; } }

• Answer:

  You can execute the block with completionBlock(doc). [doc openWithCompletionHandler:^(BOOL success) { // Can I call the completionBlock from above in here? // How do I pass back the opened UIDocument completionBlock(doc); }]; Let's assume that you have the following method implemented in the class that will be calling your openVacation method: -(void)vacationOpened:(UIManagedDocument *)vacation { NSLog(@"My Vacation: %@", vacation.description); } A sample line of code that would call your openVacation method would be: [MyVacationsHelper openVacation:@"MyVacation1" usingBlock:^(UIManagedDocument *vacation){ [self vacationOpened:vacation]; }]; The (UIManagedDocument *vacation) after the caret means that when you execute the block using the parentheses notation -- as in completionBlock(doc) --, you need to list a (UIManagedDocument *) as a parameter. The value of that parameter will be referred to as vacation inside the specified block. What I did in my block code sample above was call a method in my current class (self) and pass the parameter along to that method so that I could use it as needed (I just did an NSLog here to make sure that it worked).