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尽管我遇到了错误，但我正在关注 Paul Hudson 关于程序化导航的文章。

我使用三个简单的视图重新创建了错误。我要做的是从 ContentView -> ChildViewOne -> ChildViewTwo -> ContentView 移动。

我从 ChildViewTwo -> ContentView 收到以下错误：

2021-05-20 15:06:44.346713+1200 Test[7756:137785] [Assert] UIScrollView 不支持多个观察者实现observeScrollView:willEndDraggingWithVelocity:targetContentOffset:unclampedOriginalTarget:。滚动视图 < TtC7SwiftUIP33_BFB370BA5F1BADDC9D83021565761A4925UpdateCoalescingTableView: 0x7fb75a8df000; 基类 = UITableView; 帧 = (0 0; 390 844); clipsToBounds = YES; 手势识别器 = <NSArray: 0x6000016fe730>; 层 = <CALayer: 0x60000181a960>; 内容偏移：{0，-239}；内容大小：{390, 169.33333333333334}；调整内容插入：{239, 0, 34, 0}; 数据源：< TtGC7SwiftUIP13$7fff56921d2819ListCoreCoordinatorGVS_20SystemListDataSourceOs5Never_GOS_19SelectionManagerBoxS2：0x7fb75980e410>>，新观察者<TtGC7SwiftUI41StyleContextSplitViewNavigationControllerVS_19SidebarStyleContext : 0x7fb758855000>，移除旧的观察者 < TtGC7SwiftUI41StyleContextSplitViewNavigationControllerVS_19SidebarStyleContext : 0x7fb75902ca00>

返回 ContentView 时，我也会获得双重导航。

内容视图

struct ContentView: View {
    
    @State private var isShowingChildOne = false
    
    var body: some View {
        
        NavigationView {
            
            List {
                Text("Hello World")
                Text("Hello World")
                Text("Hello World")
            }
            
            .toolbar {
                ToolbarItem(placement: .navigationBarTrailing) {
                    VStack {
                        
                        // Programmatic navigation here
                        NavigationLink(destination: ChildViewOne(), isActive: $isShowingChildOne) { EmptyView() }
                        Button("Next") {
                            self.isShowingChildOne = true
                        }
                    }
                }
            }.navigationTitle("ContentView")
        }
    }
}

ChildViewOne

struct ChildViewOne: View {
    
    var body: some View {
        
        List(0..<5) { item in
            
            NavigationLink(destination: ChildViewTwo()) {
                Text("Hello")
            }.navigationTitle("Child One")
        }
    }
}

子视图二

struct ChildViewTwo: View {
    
    @State private var isShowingContentView = false
    
    var body: some View {
        
        Text("Hello")
            
            .navigationTitle("Child Two")
            
            .toolbar {
                ToolbarItem(placement: .navigationBarTrailing) {
                    VStack {
                        
                        // Programmatic navigation here
                        NavigationLink(destination: ContentView(), isActive: $isShowingContentView) { EmptyView() }
                        Button("Add") {
                            self.isShowingContentView = true
                        }
                    }
                }
            }
    }
}
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