How to instantiate a navigation controller from another view controller? - ios

Question

My goal is whenever i click a button on a first view controller, then it will navigate to another controller which is a navigation controller.
firstViewController and secondViewController has no connection or anything.
Picture
I used this code
#IBAction func buttonTapped(sender: UIButton) {
let storyboard = UIStoryboard(name: "Main", bundle: nil)
let vc = storyboard.instantiateViewControllerWithIdentifier("secondViewCtrl") as! SecondViewController
self.presentViewController(vc, animated: true, completion: nil)
}
The reason why i instatiate so that I could pass data like
vc.name = "Myname"
The problem with this code is that it doesn't present navigation bar and as well as the tab bar. What should I do to show both?
Updated question
#IBAction func buttonTapped(sender: UIButton) {
guard let tabBarController = tabBarController else { return }
tabBarController.selectedIndex = 1
let storyboard = UIStoryboard(name: "Main", bundle: nil)
let vc = storyboard.instantiateViewControllerWithIdentifier("trackYourGenie") as! TrackYourGenieViewController
let navController = tabBarController.viewControllers![1]
let secondViewController = navController.topViewController
vc.name = "Myname"
}

Answer 1

You are instantiating the view controller hence you wouldn't get the navigation bar. To get the navigation bar please instantiate navigation controller and since the second view is only child you would get the second view by default.
#IBAction func buttonTapped(sender: UIButton) {
let storyboard = UIStoryboard(name: "Main", bundle: nil)
let vc = storyboard.instantiateViewControllerWithIdentifier("Navigation Controller Id") as! UINavigationController
self.presentViewController(vc, animated: true, completion: nil)
}
The above code should give you the navigation bar.

Answer 2

A safe approach:
guard let tabBarController = tabBarController else { return }
tabBarController.selectedIndex = 1
If you need to access to your tabBarController to pass datas you can do simply:
let navController = tabBarController.viewControllers[1]! as! UINavigationController
let secondViewController = navController.topViewController
Your method could be:
#IBAction func buttonTapped(sender: UIButton) {
guard let tabBarController = tabBarController else { return }
let navController = tabBarController.viewControllers[1]! as! UINavigationController
let secondViewController = navController.topViewController as! SecondViewController
secondViewController.name = "my name"
tabBarController.selectedIndex = 1
}

Answer 3

In your case, the following code should be sufficient :
self.tabBarController.selectedIndex = 1
As UITabBarController is your rootViewController, you can access it with self.tabBarController. You don't have to instantiate UINavigationController as it is in the storyboard.

Answer 4

I can see from your StoryBoard that you have a TabBarController. If your configuration is that and FirstViewController is on first tab and SecondViewController on second tab, you can just change TabBarController selectedIndex property:
#IBAction func buttonTapped(sender: UIButton) {
tabBarController?.selectedIndex = 1
}
If you want to pass data to SecondViewController you can try one of these solutions:
let controller = tabBarController.viewControllers[1] as SecondViewController!
controller.data = "some data"
This soultion could not work since SecondViewController is not ready yet.
Create a singleton class where to save data, then retrieve data in SecondViewController viewDidLoad method
Save data in UserDefaults, then retrieve data in SecondViewController viewDidLoad method (bad solution if information doesn't have to be persistent)
Extend UITabBarController and use it, create a custom var in tabBarController, put data in that variable and then retrieve data in SecondViewController viewDidLoad method
Then clear data if needed.

Answer 5

Navigation will not work from firstViewController as to navigate something we need UINavigationController.
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