How to push and present to UIViewController programmatically without segue in iOS Swift 3

Question

I am using this code for push SHOW and MODALLY programmatically in iOS Objective C.
And now want to know about Swift 3.

NewsDetailsViewController *vc =  instantiateViewControllerWithIdentifier:@"NewsDetailsVCID"]; vc.newsObj = newsObj; //--this(SHOW) [self.navigationController pushViewController:vc animated:YES];   //-- or this(MODAL) [self presentViewController:vc animated:YES completion:nil];   

Answer 1

Push

do like

let storyboard = UIStoryboard(name: "Main", bundle: nil) let vc = storyboard.instantiateViewControllerWithIdentifier("NewsDetailsVCID") as NewsDetailsViewController   vc.newsObj = newsObj  navigationController?.pushViewController(vc,  animated: true) 

or safer

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

present

   let storyboard = UIStoryboard(name: "Main", bundle: nil)    let vc = self.storyboard?.instantiateViewControllerWithIdentifier("NewsDetailsVCID") as! NewsDetailsViewController       vc.newsObj = newsObj            present(vc!, animated: true, completion: nil)   

or safer

   if let vc = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "NewsDetailsVCID") as? NewsDetailsViewController      {       vc.newsObj = newsObj     present(vc, animated: true, completion: nil)     } 

Answer 2

With an elegant way.

Create an Navigatable protocol:

protocol Navigatable {     /// Storyboard name where this view controller exists.     static var storyboardName: String { get }       /// Storyboard Id of this view controller.     static var storyboardId: String { get }      /// Returns a new instance created from Storyboard identifiers.     static func instantiateFromStoryboard() -> Self } 

Create a default instantiate controller implementation:

/**  Extension of Navigatable protocol with default implementations.  */ extension Navigatable {     static func instantiateFromStoryboard() -> Self {         let storyboard = UIStoryboard(name: self.storyboardName, bundle: nil)         guard             let viewController = storyboard                 .instantiateViewController(withIdentifier: self.storyboardId) as? Self else {                     fatalError("Cannot instantiate the controller.")         }          return viewController     } } 

Extends the UIViewController to push a view controller:

extension UIViewController {     /**      Pushes a view controller of the provided type.       - Parameter viewControllerType: Type of view controller to push.      - Parameter completion: Function to be executed on completion.      Contains the view controller that was pushed when successful and nil otherwise.      */     func pushViewControllerOfType<T: Navigatable>(viewControllerType: T.Type, completion: (T) -> Void) {         let viewController = T.instantiateFromStoryboard()         if let vc = viewController as? UIViewController {             self.pushViewController(vc, animated: true)         }         completion(viewController)     }       /**      Pushes a view controller of the provided type.       - Parameter viewControllerType: Type of view controller to push.      */     func pushViewControllerOfType<T: Navigatable>(viewControllerType: T.Type) {         self.pushViewControllerOfType(viewControllerType: viewControllerType) { _ in }     } } 

Then you can use the Navigatable protocol for a specific view controller.

class MySuperViewController {    override func viewDidLoad() {       ...    }    // ... } extension MySuperViewController: Navigatable {     static var storyboardName: String {         return "Main"     }      static var storyboardId: String {         return "MySuperViewControllerId" // From your story board name Main     } }  // Instantiate your controller let vc = MySuperViewController.instantiateFromStoryboard()  // Or // // Push your view controller  // testViewController.swift  self.pushViewControllerOfType(viewControllerType: MySuperViewController)