Pass @StateObject argument to View's default initializer using weak reference

Question

Question

I have the following ObservableObject and SwiftUI view.

class ExampleState: ObservableObject {}

struct ExampleView: View {
    @StateObject var state = ExampleState()

    var body: some View {
        EmptyView()
    }
}

And I want to pass state to the view from a UIKit view.

class ExampleViewController: UIViewController {
    var state = ExampleState()
    func test() -> some View {
        ExampleView(state: state) // A compile error occurs on this line
    }
}

But I got compile error on initializer calling. And the error message says "Reference to property 'state' in closure requires explicit use of 'self' to make capture semantics explicit"

First, I do not understand why this is closure.

Second, when I followed the error message and put self, a memory leak occurred. So could you tell me if I can make it weak reference.

Environment

iOS 16
Xcode 14.3.1

vadian · Accepted Answer · 2023-09-01 14:42:03Z

4

The weak reference is @ObservedObject

struct ExampleView: View {
    @ObservedObject var state : ExampleState

    var body: some View {
        EmptyView()
    }
}

Use @StateObject if the view owns the object.
Use @ObservedObject if the object is passed from another view or class.

But creating a SwiftUI view inside an UIViewController makes no sense. Interoperability between UIKit and SwiftUI must be performed with UIHostingView/UIHostingController and UIViewRepresentable

edited Sep 1, 2023 at 14:42

answered Sep 1, 2023 at 14:33

vadian

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