Replace the managed object context of a NSPersistentDocument by a context created by MagicalRecord.

gistfile1.m

#import <Cocoa/Cocoa.h>


@interface SMDocument : NSPersistentDocument

@end

SMDocument.m

#import "SMDocument.h"

@implementation SMDocument

- (id)init {
    self = [super init];
    if (self) {
  	  NSManagedObjectContext *context = self.managedObjectContext;
		  if (context.concurrencyType != NSMainQueueConcurrencyType) {
			  NSUndoManager *undoManager = context.undoManager;
			  NSPersistentStoreCoordinator *coordinator = context.persistentStoreCoordinator;
			  context = [NSManagedObjectContext newMainQueueContext];
			  context.persistentStoreCoordinator = coordinator;
			  context.undoManager = undoManager;
			  self.managedObjectContext = context;
		  }
		
		  NSAssert1(self.managedObjectContext.concurrencyType == NSMainQueueConcurrencyType, @"Wrong concurrency type: %li", self.managedObjectContext.concurrencyType);
    }
    return self;
}

@end

Great! Have you tested this idea? I would never have thought that setting the property managedObjectContext on NSDocument could be authorized (yes, it is said in the doc that you can...)!!!! How did you get this idea?