Question 129961 in Xcode Question posted in
Whether you're new to Xcode or an experienced developer, our archive has everything you need to know about this integrated development environment (IDE). From basic functionalities to advanced features, our archive covers a wide range of Xcode-related questions and answers. Browse our archive now and find solutions to your Xcode questions, and take your app development skills to the next level

Xcode – passing viewController as a parameter in function

I want to pass viewController type as a function just like the code below

extension UIViewController {
    func switchScreen(storyboardName:String,viewControllerName:String,vcc:UIViewController) {
        let mainStoryboard = UIStoryboard(name: storyboardName, bundle: Bundle.main)
        if let viewController = mainStoryboard.instantiateViewController(withIdentifier: viewControllerName) as? vcc {
            self.present(viewController, animated: true, completion: nil)
        }
    }
}

but xcode returns an error that says Cannot find type 'vcc' in scope

I tried adding .Type in the parameter after UIViewController but the error is the same.
any solutions?

Tags:

2

Answers


  1. 0

    Use generic param

    extension UIViewController {
    func switchScreen<T: UIViewController>(storyboardName:String,viewControllerName:String,vcc:T) {
        let mainStoryboard = UIStoryboard(name: storyboardName, bundle: Bundle.main)
        if let viewController = mainStoryboard.instantiateViewController(withIdentifier: viewControllerName) as? T {
            self.present(viewController, animated: true, completion: nil)
        }
    }
}
    Login or Signup to reply.
  2. 0

    The third parameter must be a type, not an instance

    extension UIViewController {
    func switchScreen<T : UIViewController>(storyboardName: String, viewControllerName: String, type: T.Type) {
        let mainStoryboard = UIStoryboard(name: storyboardName, bundle: Bundle.main)
        if let viewController = mainStoryboard.instantiateViewController(withIdentifier: viewControllerName) as? T {
            self.present(viewController, animated: true, completion: nil)
        }
    }
}

    and call it

    switchScreen(storyboardName: "Main", 
             viewControllerName: "Foo", 
             type: LoginViewController.self)

    But as instantiateViewController and also present don’t care about the static type you don’t need it, this is sufficient

    extension UIViewController {
    func switchScreen(storyboardName: String, viewControllerName: String) {
        let mainStoryboard = UIStoryboard(name: storyboardName, bundle: Bundle.main)
        let viewController = mainStoryboard.instantiateViewController(withIdentifier: viewControllerName)
        self.present(viewController, animated: true, completion: nil)
    }
}

    To avoid a crash you could add an enum with the available view controller identifiers and pass this type in the second parameter for example

    enum ControllerIdentifier : String, RawRepresentable {
    case foo, bar
}

extension UIViewController {
    func switchScreen(storyboardName: String, viewControllerName: ControllerIdentifier) {
        let mainStoryboard = UIStoryboard(name: storyboardName, bundle: Bundle.main)
        let viewController = mainStoryboard.instantiateViewController(withIdentifier: viewControllerName.rawValue)
        self.present(viewController, animated: true, completion: nil)
    }
}
    Login or Signup to reply.
Please signup or login to give your own answer.

Back To Top
Search