First, I would try to just see if you are assigning a value by nslog
NSLog(@"%@", [_vinhoArray objectAtIndex:indexPath.row]);
Then if you are getting something in the log, you can try
self.stringTest = [_vinhoArray objectAtIndex:indexPath.row];
if you are storing NSStrings in your array.
Try this,
create your string in AppDelegate.h
@property (nonatomic, retain) NSString *myTitleString;
Now anywhere you want to access this string, you are going to need to include the appDelegate at the top
#import "AppDelegate.h"
and then use this to access it
AppDelegate *AppDelegate = [[UIApplication sharedApplication] delegate];
assign it with
AppDelegate.MyTitleString = //whatever you are going to assign it with;
in your other view controller you will do the same thing, import the appdelegat.h at the top, create the app delegate and give it's value to your title
NSString *MyStringInTheDifferentController = AppDelegate.MyTitleString;