How to push and present to UIViewController programmatically From a XIB in iOS Swift 3

Question

Im working on a project in swift 3.0 and I use the following mechanism to navigate from one UIViewController to another.

if let viewController = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "MP3ViewController") as? MP3ViewController {
  viewController.mediaDetails = mp3Details
  if let navigator = navigationController {
      navigator.pushViewController(viewController, animated: true)
  }
}

However when I try the same mechanism in the XIB file it gives me an error

Error: saying 'use of unresolved identifier navigationController'

How can I create a navigationController instance here? bellow Ive shown the code of my XIB class that gives me an error

if let categoriesController = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "CategoriesViewController") as? CategoriesViewController {
  categoriesController.categoryName = trimmedCategortyNameText

  if let navigator = navigationController {
      navigator.pushViewController(categoriesController, animated: true)
  }
}

Answer 1

Consider this sample:

    let sampleVC = SampleViewController(nibName: "SampleViewController", bundle: nil)
    self.navigationController?.pushViewController(sampleVC, animated: true)

Edit

As per your requirement, you need to navigation from UIView to UIViewController. You can achieve this in two way

• using delegate/callback
• using reference of NavigationController

I will be showing you the second way.

Take a variable of UINavigationController in AppDelegate

In AppDelegate

var navController : UINavigationController?

Then assign the navigation controller to this variable from where you are navigating to UIView. (Let's say from SampleViewController you are adding UIView, then write)

In ViewController (This is my MainVC)

    let appDelegate = UIApplication.shared.delegate! as! AppDelegate
    appDelegate.navController = self.navigationController

Then in UIView class ( SampleView in my case)

    let appDelegate = UIApplication.shared.delegate! as! AppDelegate
    
    let sampleVC = SampleViewController(nibName: "SampleViewController", bundle: nil)

    appDelegate.navController?.pushViewController(sampleVC, animated: true)

I verified this.

Answer 2

You can do like this:

If you are using storyboard :

if let viewController = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "MP3ViewController") as? MP3ViewController {
        viewController.mediaDetails = mp3Details
        if let navigator = self.navigationController {
            navigator.pushViewController(viewController, animated: true)
        }else{
            let navigation  = UINavigationController(rootViewController:viewController)
            self.present(navigation, animated: true, completion: nil)
        }
}

With Xib

Initialize a instance of UIViewController like this:

   let  vc =  MP3ViewController(nibName:"MP3ViewController",bundle:Bundle.main)
   vc.mediaDetails = mp3Details
    if let navigator = self.navigationController {
        navigator.pushViewController(viewController, animated: true)
    }else{
        let navigation  = UINavigationController(rootViewController:viewController)
        self.present(navigation, animated: true, completion: nil)
    }

Answer 3

You can use the same mechanism with Xib using Appdelegate

let storyboard = UIStoryboard(name: "Main", bundle: nil)
        let currentOrderVC = storyboard.instantiateViewController(withIdentifier: "yourVcId") as! YourVC

        var nav1 = UINavigationController()
        nav1.viewControllers = [currentOrderVC]

        UIApplication.shared.keyWindow?.rootViewController
        UIApplication.shared.keyWindow?.rootViewController = nav1
        UIApplication.shared.keyWindow?.makeKeyAndVisible();