如何定义和使用@namespace var a view

Question

完全有可能在视图外部定义@namespace var并将其传递给视图。例如，在

State

类中这样做？

I包括了一个匹配动画的基线代码。我尝试了几件事（例如

this），没有成功，这意味着动画不匹配。我已经看到了一些解决方案，但是@namespace var始终是我无法做的视图属性。

import SwiftUI
import PlaygroundSupport

enum Flow {
    case initial
    case searching
}

class State: ObservableObject {
    @Published var flow: Flow = .initial
}

let state = State()

struct Container: View {
    @Namespace var namespace
    @ObservedObject var state: State

    var body: some View {
        VStack {
            SubView1(state: state, namespace: namespace)
            SubView2(state: state, namespace: namespace)
        }
        .onTapGesture {
            withAnimation(.spring()) {
                if state.flow == .initial {
                    state.flow = .searching
                } else {
                    state.flow = .initial
                }
            }
        }
        .frame(width: 300, height: 300)
    }
}

struct SubView1: View {
    @ObservedObject var state: State
    var namespace: Namespace.ID

    var body: some View {
        HStack {
            Text("Lorem")
            Spacer()

            if state.flow == .initial {
                Text("Ipsum")
                    .matchedGeometryEffect(id: "id", in: namespace)
                Text("|")
            }
            Image(systemName: "person.circle.fill")
        }
    }
}

struct SubView2: View {
    @ObservedObject var state: State
    var namespace: Namespace.ID

    var body: some View {
        VStack {
            Text("Headline")
            if state.flow == .searching {
                Text("Ipsum")
                    .matchedGeometryEffect(id: "id", in: namespace)
            }
        }
    }
}

PlaygroundPage.current.setLiveView(Container(state: state))

Answer 1

Namespace

是一个

DynamicProperty

，并且仅在a

DynamicProperty

中起作用，因为它们在更新时获得了价值。