Instance member cannot be used on type in ARKitVision example

Question

MyAppleQuestions OP

Created Jun ’18

Replies 6

Boosts 0

Views 1.4k

Participants 3

The Apple ARKitVision example has the following declaration in the ViewController.swift file:

// The view controller that displays the status and "restart experience" UI.

private lazy var statusViewController: StatusViewController = {

return children.lazy.compactMap({ $0 as? StatusViewController }).first!

}()

However, if I copy the same views and source files and incorporate them into another test storyboard/project I get the error message "Instance member 'children' cannot be used on type 'StatusViewController'". So, why does this work on the ARKitVision example but it does not work if I set it up myself from scratch? What else is the ARKitVision example doing to get this working? Thanks 😊

Boost

Answer 1

MyAppleQuestions OP

Jun ’18

I don't understand, the class inherits from UIViewController and yet Xcode does not see the 'children' var as being available. Why would that be the case?

0

Answer 2

Claude31 OP

Jun ’18

How did you define StatusViewController ? Did you import the class definition as well ?

0

Answer 3

LittleyLv OP

Jun ’18

Do you have "Embed segue to status view controller" in your View Controller Scene?

0

Answer 4

Claude31 OP

Jun ’18

It inherits from StatusViewController which inherits from UIViewController.

0

Answer 5

MyAppleQuestions OP

Jun ’18

Yes, I imported the StatusViewController class and it too subclasses UIViewController.

0

Answer 6

MyAppleQuestions OP

Jun ’18

Yes, I have "Embed segue to status view controller" in my View Controller Scene.

Both ViewController and StatusViewController subclass UIViewController. In the ARKitVision ViewController.swift class if I start typing "children" it recognises it as a var that can be used. If I go to my own project with exactly the same classes, exactly the same code and start typing "children" it does not recognise it as a var that can be used. If I delete the "private lazy var statusViewController: StatusViewController" declaration the code compiles and runs perfectly. I can also programmatically create the StatusViewController. For some unexplained reason, even though I have subclassed UIViewController, used exactly the same code as in ARKitVision, my subclass cannot gain access to the parents variables, and hence displays the above message.

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