Programmatically switch view controller to show views in Tab Bar Controller - ios

Question

I am trying to figure out how I can programmatically switch the views from one view controller to a first view controller in a Tab bar controller when I press a button.
Currently I have a view controller with three buttons. When I press a button I would like to then switch. This is the following code I have for this screen. It is called the second view controller.
import UIKit
class SecondViewController: UIViewController {
//Button Outlets
#IBOutlet var ButtonEndOfShift: UIButton!
#IBOutlet var ButtonMultiTimes: UIButton!
#IBOutlet var ButtonEndAndLunch: UIButton!
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
//hides tab bar controller
self.tabBarController?.tabBar.hidden = true
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
//Changes screen for End Of Shift Button
#IBAction func ChangeNextViewLow(sender: AnyObject) {
self.performSegueWithIdentifier("segue", sender: nil)
}
//Changes screen for Lunch and End Of Shift Button
#IBAction func ChangeNextViewMedium(sender: UIButton) {
}
//Changes screen for Multiple Times button
#IBAction func ChangeNextViewHigh(sender: UIButton) {
}
}

Answer 1

I have added UITabBarController in Storyboard like below please see images.
Then i have written following functions for your help.
// For navigate to Tabbar Controller
#IBAction func btnClick () {
self.performSegueWithIdentifier("GoToTabBar", sender: nil)
}
// For switching between tabs
func switchTab (index : Int) {
self.tabbarController.selectedIndex = index
}
You can also set UITabBarController as your application RootViewController.

Answer 2

Implement Code For didFinishLaunchingWithOptions
self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
firstViewController *firstTab = [[firstViewController alloc] initWithNibName:#"firstViewController" bundle:nil];
UINavigationController *navCntrl1 = [[UINavigationController alloc] initWithRootViewController:firstTab];
secViewController *secTab = [[firstViewController alloc] initWithNibName:#"secViewController" bundle:nil];
UINavigationController *navCntrl2 = [[UINavigationController alloc] initWithRootViewController:secTab];
thirdViewController *thirdTab = [[thirdViewController alloc] initWithNibName:#"thirdViewController" bundle:nil];
UINavigationController *navCntrl3 = [[UINavigationController alloc] initWithRootViewController:thirdTab];
UITabBarController *tabBarController = [[UITabBarController alloc] init];
tabBarController.viewControllers = #[navCntrl1, navCntrl2, navCntrl3];
[self.window setRootViewController:tabBarController];
[self.window makeKeyAndVisible];