Recursive Core Data saves with RAC. Works with nested contexts!

gistfile1.m

@implementation NSManagedObjectContext (INAdditions)

- (RACSignal *)in_saveChanges
{
  return [[RACSignal startEagerlyWithScheduler:RACScheduler.scheduler block:^(id<RACSubscriber> subscriber) {
		__block void (^recursiveBlock)(NSManagedObjectContext *);
		recursiveBlock = [^(NSManagedObjectContext *context) {
			[context performBlock:^{
				NSError *error = nil;
				[context save:&error];
				// Not calling -sendError: at this point because we still want the
				// parent contexts to be flushed in case they have any of their own
				// changes that are not dependent on this save.
				if (context.parentContext) {
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Warc-retain-cycles"
					recursiveBlock(context.parentContext);
#pragma clang diagnostic pop
				} else {
					recursiveBlock = nil;
					[subscriber sendCompleted];
				}
			}];
		} copy];
		recursiveBlock(self);
	}] deliverOn:RACScheduler.mainThreadScheduler];
}

@end

// I use it for cool things like preventing app termination until a full save has completed:

- (NSApplicationTerminateReply)applicationShouldTerminate:(NSApplication *)sender
{
  [[_backgroundContext in_saveChanges] subscribeCompleted:^{
		[NSApp replyToApplicationShouldTerminate:YES];
	}];
	return NSTerminateLater;
}