I have a books app with a UISearchBar, where the user types any book name and gets search results (from ext API call) below as he types.

I am using a singleton variable in my app called retrievedArray which stores all the books.

@interface Shared : NSObject {
    NSMutableArray *books;
}

@property (nonatomic, retain) NSMutableArray *books;

+ (id)sharedManager;

@end

This is accessed in multiple .m files using NSMutableArray *retrievedArray; ...in the header file

retrievedArray = [[Shared sharedManager] books];

My question is how do I ensure that the values inside retrievedArray remain synchronized across all the classes.

Actually the values inside retrievedArray gets added through an NSXMLParser (i.e. through external web service API). There is a separate XMLParser.m file, where I do all the parsing and fill the array. The parsing is done on a separate thread.

    - (void) run: (id) param  {
        NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];

        NSXMLParser *parser = [[NSXMLParser alloc] initWithContentsOfURL: [self URL]];
        [parser setDelegate: self];
    [parser parse];
        [parser release];

        NSString *tmpURLStr = [[self URL]absoluteString];

        NSRange range_srch_book = [tmpURLStr rangeOfString:@"v1/books"];

        if (range_srch_book.location != NSNotFound) 
            [delegate performSelectorOnMainThread:@selector(parseDidComplete_srch_book) withObject:nil waitUntilDone:YES];

        [pool release];
    } 


    - (void) parseXMLFile: (NSURL *) url
    {   
        NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
        [self setURL: url];
        NSThread* myThread = [[NSThread alloc] initWithTarget:self
                                                     selector:@selector(run:)


object: nil];
    [retrievedArray removeAllObjects];
    [myThread start];
    [pool release];
}

There seems to be some synchronization issues if the user types very quickly (It seems to be working fine if the user types slowly)....So there are 2 views in which the content of an object in this shared array item is displayed; List and Detail. If user types fast and clicks on A in List view, he is shown B in detail view...That is the main issue.

I have tried literally all the solutions I could think of, but am still unable to fix the issue. Please suggest some suitable fixes.