Setup Core Data SQLite db for use with iCloud

gistfile1.m

//Some scattered methods for setting up iCloud storage of a SQLite Core Data managed database.


//define your ubiquity container id
-(NSString*)ubiquityContainerIdentifier {
    //should match what is in your app's entitlement file
    return [NSString stringWithFormat:@"%@.%@", @"<YOUR TEAM IDENTIFIER>", [[NSBundle mainBundle] bundleIdentifier]];
}

//where you're going to store your database
- (NSURL*)ubiquitousPersistentStoreURL {
    NSFileManager* manager = [NSFileManager defaultManager];
    
    //locate and/or create database folder
    NSURL* containerURL = [manager URLForUbiquityContainerIdentifier:[self ubiquityContainerIdentifier]];
    NSString* directoryName = @"<DATABASE FOLDER NAME>.nosync";
    NSString* directoryURL = [containerURL URLByAppendingPathComponent:directoryName isDirectory:YES];
    
    if(![manager fileExistsAtPath:[directoryURL path]]) {
        NSError* error = nil;
        
        if(![manager createDirectoryAtURL:directoryURL withIntermediateDirectories:NO attributes:nil error:&error]) {
            NSLog(@"error creating container directory for ubiquitous storage: %@", error);
            return nil;
        }
    }
    
    //append db name
    return [[NSURL URLWithString:directoryPath] URLByAppendingPathComponent:@"<DATABASE NAME>" isDirectory:NO];
}

//setup store in an assumed _persistentStoreCoordinator
-(void)addPersistentStoreToCoordinator {
    NSMutableDictionary* storeOptions = [NSMutableDictionary dictionary];
    [storeOptions setObject:[NSNumber numberWithBool:YES] forKey:NSMigratePersistentStoresAutomaticallyOption];
    [storeOptions setObject:[NSNumber numberWithBool:YES] forKey:NSInferMappingModelAutomaticallyOption];
        
    //setup your store with iCloud options
    [storeOptions setObject:[[NSBundle mainBundle] bundleIdentifier] forKey:NSPersistentStoreUbiquitousContentNameKey];

    //locate and/or create a location for iCloud to store it's transaction logs
    NSFileManager* manager = [NSFileManager defaultManager];
    NSURL* containerURL = [manager URLForUbiquityContainerIdentifier:[self ubiquityContainerIdentifier]];
    NSString* directoryName = @"TransactionLogs";//recommended, but you can change this to whatever
    NSURL* directoryURL = [containerURL URLByAppendingPathComponent:directoryName isDirectory:YES];

    if(![manager fileExistsAtPath:[directoryURL path]]) {
        NSError* error = nil;                
        if(![manager createDirectoryAtURL:directoryURL withIntermediateDirectories:NO attributes:nil error:&error]) {
            NSLog(@"error creating transaction logs directory for ubiquitous storage: %@", error);
            return nil;
        }
    }
    [storeOptions setObject:directoryURL forKey:NSPersistentStoreUbiquitousContentURLKey];

    //add store to coordinator
    if(![_persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeUrl options:storeOptions error:&error]) {
        //handle error
    }

    //listen for ubiquitous changes
    [[NSNotificationCenter defaultCenter]addObserver:self selector:@selector(ubiquitousStoreDidChange:) name:NSPersistentStoreDidImportUbiquitousContentChangesNotification object:_persistentStoreCoordinator];
}

- (void) ubiquitousStoreDidChange:(NSNotification*)notification {    
  //new data from iCloud available, merge into our managed object context
  [[self moc] mergeChangesFromContextDidSaveNotification:notification];
  NSError* error = nil;
  [[self moc] save:&error];

  if(error) {
    //something went wrong
  }
}