Share Data Between View Controller and Container View

Question

I have a view controller that has a segue to a second view controller, and I passed some data to the second one in prepare for segue. The problem is: the second view controller has a container view which I need to share that data with. I tried using prepare for segue but it didn't work in this case.

Update:

View Controller code:

class ViewController: UITableViewController, ContainerViewDelegate {

   var myContainerView = ContainerView()
   var id: String!

   override func viewDidLoad() {
        super.viewDidLoad()
        id = "123"
        myContainerView.delegate = self
   }

   func initialize() -> String {
        return id
   }
}

Container view code:

protocol ContainerViewDelegate {
   func initialize() -> String
}

class ContainerView: UICollectionViewController {

   var delegate: ContainerViewDelegate!
   var id: String!
   override func viewDidLoad() {
       super.viewDidLoad()
       id = delegate.initialize()
       print(id)
   }
}

I get error: fatal error: unexpectedly found nil while unwrapping an Optional value at the line: id = delegate.initialize()

Answer 1

You are on the right track to setup the delegate.

In Storyboard:

• create a Segue of type Embed Segue from the ContainerView to the ViewController to embed.
• Select the segue and set a Identifier.

In Code, in prepareForSegue():

• Set the myContainerView propert

• Set the delegate

  class ViewController: UITableViewController, ContainerViewDelegate {
      var myContainerView:ContainerView? // we do initialize it in prepareForSegue()
      var id: String!
  
      override func viewDidLoad() {
          super.viewDidLoad()
          id = "123"
          // myContainerView.delegate = self //myContainerView is nil here. We set it in prepareForSegue
      }
  
      func initialize() -> String {
          return id
      }
  
      let embedSegueID = "the identifier you set to your embed segue in Storyboard"
  
      override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
          if (segue.identifier == embedSegueID) {
              let dvc = segue.destination as! ContainerView
              // Now you have a pointer to EmbeddedViewController.
              // You can save the reference to it, or pass data to it.
              myContainerView = dvc
              myContainerView.delegate = self
          }
          print(segue.identifier)
      }
  }
  

---

If you want to pass data from your ViewController to AnotherViewController which is embedded in your destinationViewController (how I understand your question), I would:

• pass it to destinationViewController as in the example above (prepareForSegue)
• than pass it to AnotherViewController in viewWillAppear() from within destinationViewController.

In this case, how I understand your usecase, you do not need the delegate and can remove all delegate related code (initialize, the ContainerViewDelegate protocol, the property var delegate: ContainerViewDelegate! and all calls to it.