I'm new to swift. How can I call func print on my CallerViewController class

   class CallerViewController: UIViewController {

       var subViewController: SubViewController!
       override func viewDidLoad() {
          super.viewDidLoad()
             subViewController = SubViewController() // this is throwing Missing argument for parameter 'coder' in call
             subViewController.printHello()
       }
   }

Subclass

   class SubViewController: SuperViewController {
       func printHello(){
          print("Hello World")
       }
   }

Super class

   class SuperViewController: UIViewController {
   }

CodePudding user response：

You can inherit the SubViewController in CallerViewController

 class CallerViewController: SubViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        printHello()
    }
}

class SubViewController: SuperViewController {
    func printHello() {
        print("Hello World")
    }
}

class SuperViewController: UIViewController {
    
}

CodePudding user response：

You are getting an error because you are not creating your UIViewController instance called SubViewController the correct way. Here is some guideline how to create UIViewController . For the sake of this guideline I call it TestViewController. Just to mention the guideline is using Storyboard based layout (as you do)

1. create new swift file and create TestViewController with this code:

    class TestViewController: UIViewController {
   
      override func viewDidLoad() {
        super.viewDidLoad()
      }
   
      func printHello(){
        print("Hello World")
      }
    }
   

2. Create new UIViewController in main.storyboard file by clicking " " button in right top corner and typing "UIViewController"

3. Assign TestViewController as a class to your storyboard UIViewController

4. Assign some identifier (TestIdentifier) to your storyboard UIViewController

5. you can finally create TestViewController instance from storyboard by calling this function:

    func createUIViewControllerAndCallPrintHello() {
    let storyboard = UIStoryboard(name: "Main", bundle: nil)
    let testViewController =   storyboard.instantiateViewController(withIdentifier: "TestIdentifier") as! TestViewController
    testViewController.printHello()
    }