context not calling performblock - iphone

Question

http://www.fileconvoy.com/dfl.php?id=g021ae486d8d8acb3999343609097fcba7f7befa53
this is the link to an assignment app which i got for my homework it most of its concepts taken from the stanford cs193p course as iam studing that too, this app has 3 modules
1 camera
2 map
3 contacts
the camera and map modules are working fine not as hoped but fine cut in the contacts module I
am using core data model to store contacts from contacts directory which you'll see when you run the app.
Now the problem is that my view adds the contacts to the core data but they are not showing in the table so when i tried to debug the application i saw that the method
[self.managedObjectContext performBlockAndWait:^{}];
is not calling the block of code inside it thats why the data is not even getting saved in the data model let alone show in table.
very very thanks in advance...
NSURL *url = [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject];
url = [url URLByAppendingPathComponent:#"Demo Document"];
UIManagedDocument *document = [[UIManagedDocument alloc] initWithFileURL:url];
if (![[NSFileManager defaultManager] fileExistsAtPath:[url path]]) {
[document saveToURL:url
forSaveOperation:UIDocumentSaveForCreating
completionHandler:^(BOOL success) {
if (success) {
self.managedObjectContext = document.managedObjectContext;
}
}];
} else if (document.documentState == UIDocumentStateClosed) {
[document openWithCompletionHandler:^(BOOL success) {
if (success) {
self.managedObjectContext = document.managedObjectContext;
}
}];
} else {
self.managedObjectContext = document.managedObjectContext;
}
if(self.managedObjectContext==nil)
NSLog(#"nil object");