[tab setSelectedIndex:2];

[[NSUserDefaults standardUserDefaults]setObject:yourArray forKey:@"YourKey"];

NSMutableArray *array=[[NSUserDefaults standardUserDefaults]objectForKey:@"YourKey"];

override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
      if segue.identifier == "toTabController" {
        var tabBarC : UITabBarController = segue.destinationViewController as UITabBarController
        var desView: CaseViewController = tabBarC.viewControllers?.first as CaseViewController

        var caseIndex = overviewTableView!.indexPathForSelectedRow()!.row
        var selectedCase = self.cases[caseIndex]

        desView.caseitem = selectedCase
      }
    }

@IBAction func sendBtnListener(sender: AnyObject) {
        Singleton.sharedInstance.brandName = self.searchDisplayController!.searchBar.text
        self.tabBarController!.selectedIndex = 2
}

override func viewDidLoad() {
     super.viewDidLoad()

     //Nothing is printed out for this portion of code except the first time
     if !Singleton.sharedInstance.brandName.isEmpty{
         println(Singleton.sharedInstance.brandName)

     }else{

         println("Empty")
     }
 }

class Singleton {
    var name : String = ""
    class var sharedInstance : Singleton {
        struct Static {
            static let instance : Singleton = Singleton()
        }
        return Static.instance
    }

    var brandName : String {
        get{
            return self.name
        }

        set {
            self.name = newValue
        }
    }
}

class firstViewController: UIViewController ,UITabBarControllerDelegate{
let arrayName = ["First", "Second", "Third"]
    override func viewDidLoad() {
        super.viewDidLoad()

        self.tabBarController?.delegate = self
    }

    func tabBarController(_ tabBarController: UITabBarController, shouldSelect viewController: UIViewController) -> Bool {
        if viewController .isKind(of: firstsubsecoundViewController.self as AnyClass ) {
            let viewController  = tabBarController.viewControllers?[1] as! secondViewController
            viewController.arraydata = self.arrayName
       }
        return true
    }
}

class secondViewController: UIViewController {
    var arraydata:[String] = NSArray()
      override func viewDidLoad() {
        super.viewDidLoad()
        print(arraydata)
      }
}
//OutPut:- ["First", "Second", "Third"]