How to pass a local function to another object during init?

Question

How to pass a local function to another object during init?

I did the below, but got \'self\' captured by a closure before all members were initialized

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Answer 1

First, your property drawViewWrapper seems to be useless here since you can access it later with self.rootView and second, you should use [unowned self] to avoid capturing 'self' and creating a weak reference to it instead (and then avoid a retain-cycle).

So I would do something like this instead:

class ContextViewController: UIHostingController<ContentView> {
    
    init(drawView: CustomDrawView) {
        let drawViewWrapper = ContentView(
            drawView: drawView,
            dismiss: { [unowned self] in
                self.dismiss(animated: true)
            })
        super.init(rootView: drawViewWrapper)
    }

    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}

And then if you need to access it later, you can simply use self.rootView.

Answer 2

You have to call super.init() before:

class ContextViewController: UIHostingController<ContentView> {

    let drawViewWrapper: ContentView?
    
    init(drawView: CustomDrawView) {
        super.init(rootView: self.drawViewWrapper)
        self.drawViewWrapper = ContentView(
            drawView: drawView,
            dismiss: { self.dismiss(animated: true) })
    }

}

Answer 3

if it's an option for you I'd suggest making the dismiss block not part of the init but rather an optional var on the ContentView.

My solution would look kind of like:

ContentView

class ContentView: UIView {
    var dismiss: (() -> Void)?
    
    init(drawView: UIView) {
        super.init(frame: .zero)
    }
    
    ...
}

You could also indicate the dismiss block will always be there by replacing the ? with an ! (var dismiss: (() -> Void)!) so you don't have to unwrap it when calling but I wouldn't suggest that as it's not compile time safe and so not what you really want.

ContextViewController

class ContextViewController: UIHostingController<ContentView> {

    let drawViewWrapper: ContentView
    
    lazy var selfDismiss: () -> Void = { [unowned self] in
        self.dismiss(animated: true)
    }
    
    init(drawView: CustomDrawView) {
        self.drawViewWrapper = ContentView(drawView: drawView)
        super.init(rootView: self.drawViewWrapper)
        self.drawViewWrapper.dismiss = selfDismiss
    }
    
    ...
}