Question

我正在尝试实现需要委托方法的功能（例如NSUserActivity）。因此，我需要一个符合UIViewController（或类似的其他委托人），处理并保存所有必需信息的NSUserActivityDelegate。我的问题是我在界面上使用的是SwiftUI，因此我没有在使用UIViewControllers。因此，我该如何实现此功能，同时仍将SwiftUI用于UI。我尝试了什么：view1只是一个普通的SwiftUI View，可以显示（通过NavigationLink）view2，view2是要实现此功能的视图。因此，我尝试代替链接view1和view2，而是将view1链接到UIViewControllerRepresentable，然后UIHostingController(rootView: view2)处理此功能的实现，并将struct view1: View { var body: some View { NavigationLink(destination: VCRepresentable()) { Text("Some Label") } } } struct view2: View { var body: some View { Text("Hello World!") } } struct VCRepresentable: UIViewControllerRepresentable { func makeUIViewController(context: Context) -> UIViewController { return implementationVC() } func updateUIViewController(_ uiViewController: UIViewController, context: Context) { } } class implementationVC: UIViewController, SomeDelegate for functionality { // does implementation stuff in delegate methods ... override func viewDidLoad() { super.viewDidLoad() attachChild(UIHostingController(rootView: view2())) } private func attachChild(_ viewController: UIViewController) { addChild(viewController) if let subview = viewController.view { subview.translatesAutoresizingMaskIntoConstraints = false view.addSubview(subview) subview.widthAnchor.constraint(equalTo: view.widthAnchor).isActive = true subview.heightAnchor.constraint(equalTo: view.heightAnchor).isActive = true subview.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true subview.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true } viewController.didMove(toParent: self) } }添加为子视图控制器。

{{1}}

我在VC和view2之间传输数据时遇到麻烦。因此，我想知道是否有更好的方法可以在SwiftUI视图中实现这种功能。

Answer 1

您需要创建一个符合UIViewControllerRepresentable并具有Coordinator的视图，该视图可以处理所有委托功能。

例如，使用示例视图控制器和委托：

struct SomeDelegateObserver: UIViewControllerRepresentable {
    let vc = SomeViewController()
    var foo: (Data) -> Void
    func makeUIViewController(context: Context) -> SomeViewController {
        return vc
    }

    func updateUIViewController(_ uiViewController: SomeViewController, context: Context) { }
    func makeCoordinator() -> Coordinator {
        Coordinator(foo: foo)
    }

    class Coordinator: NSObject, SomeDelegate {
        var foo: (Data) -> Void
        init(vc: SomeViewController, foo: @escaping (Data) -> Void) {
            self.foo = foo
            super.init()
            vc.delegate = self
        }
        func someDelegateFunction(data: Data) {
            foo()
        }
    }
}

用法：

struct ContentView: View {
    var dataModel: DataModel

    var body: some View {
        NavigationLink(destination: CustomView(numberFromPreviousView: 10)) {
            Text("Go to VCRepresentable")
        }
    }
}

struct CustomView: View {
    @State var instanceData1: String = ""
    @State var instanceData2: Data?
    var numberFromPreviousView: Int // example of data passed from the previous view to this view, the one that can react to the delegate's functions
    var body: some View {
        ZStack {
            SomeDelegateObserver { data in
                print("Some delegate function was executed.")
                self.instanceData1 = "Executed!"
                self.instanceData2 = data
            }
            VStack {
                Text("This is the UI")
                Text("That, in UIKit, you would have in the UIViewController")
                Text("That conforms to whatever delegate")
                Text("SomeDelegateObserver is observing.")
                Spacer()
                Text(instanceData1)
            }
        }
    }
}

注意：我将VCRepresentable重命名为SomeDelegateObserver是为了更好地表明它的作用：其唯一目的是等待委托函数执行然后运行闭包（即本示例中的foo）由您提供。您可以使用此模式创建所需数量的功能，以“观察”您关心的任何委托功能，然后执行可更新UI，数据模型等的代码。在我的示例中，当SomeDelegate触发someDelegateFunction(data:)，该视图将显示“已执行”并更新数据实例变量。

在SwiftUI视图中实现委托

1 个答案: