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ios - SwiftUI：将动态数据传递给内容视图后重绘

问题描述

我有类似下面的东西，除了我在“ChildContentView”中有额外的动态手势。

我将如何强制子视图重绘/重新加载？目前，任何动态内容都会绘制一次并且不会重新加载。所有内容基本上都是静态的。

更新：需要使用let content: () -> Content而不是@State var content: () -> Content.

// ChildContentView
struct ChildContentView<Content: View>: View {
    @State var content: () -> Content

    var body: some View {
        let dragGesture = DragGesture()...

        return Group {
            self.content()
        }.gesture(dragGesture)
    }
}

// ContentView
...
@State var changingList: [FooItem] = [] <-- This is dynamically changed.  Not reflected in this code snippet.

var body: some View {
    ZStack { 
        ChildContentView {
            List(changingList) { item in
                print("\(item)")
            }
        }
    }
}
...

标签： iosswiftswiftui

解决方案

你的麻烦是 State 属性包装器

struct ChildContentView<Content: View>: View {

@State var content: () -> Content

    var body: some View {
        let dragGesture = DragGesture()...

        return Group {
            self.content()
        }.gesture(dragGesture)
    }
}

它使内容“静态”（实际上你做到了:-)）

让我们看看并尝试这个例子（复制 - 粘贴 - 在你的模拟器中运行）

import SwiftUI
struct Child<Content: View>: View {
    var content: () -> Content
    var body: some View {
        content()
    }
}

struct Item: Identifiable {
    let txt: String
    let id = UUID()
}

struct ContentView: View {
    @State var items = [Item(txt: "Alfa"), Item(txt: "Beta")]
    var body: some View {
        ZStack {
            Child {
                List(self.items) { (item) in
                    Text(item.txt)
                }
            }
            Button(action: {
                self.items.append(contentsOf: [Item(txt: "game"), Item(txt: "Delta")])
            }) {
                Text("Tap me to change items").padding().padding(.vertical, 50).background(Color.yellow)
            }
        }
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}

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