SwiftUI 中的上下文菜单未更新

Posted 2023-03-11

【中文标题】SwiftUI 中的上下文菜单未更新

【英文标题】：Context Menu not updating in SwiftUI

【发布时间】：2021-11-29 18:15:20

【问题描述】：

我正在尝试设置一个 SwiftUI .contextMenu，它带有一个可以切换 Bool 值的按钮。当Bool 切换时，上下文菜单的按钮文本应该会发生变化。但是上下文菜单不会更新。有没有办法强制更新上下文菜单？

描述问题的示例代码：

import SwiftUI

struct Item: Identifiable 
    let id = UUID()
    let user: String
    var active: Bool


struct ContentView: View 
    @State var items: [Item] = [
        Item(user: "Daniel",active: false),
        Item(user: "Jack", active: true),
        Item(user: "John", active: true)
    ]
    
    @State var isOn : Bool = false
    var body: some View 
        List 
            ForEach(items)  item in
                VStack 
                    Text("\(item.user)")
                        
                    HStack 
                        Text("Active ? ")
                        Text(item.active ? "YES": "NO")
                    
                .contextMenu
                    Button(action: 
                        let index = items.firstIndex$0.user == item.user
                        
                        items[index!].active.toggle()
                    ) 
                        Text(item.active ? "Set as Active": "Set as Inactive")
                    
                
            
        
    

【参考方案1】：

这是SwiftUI中的一个bug，在Xcode 13.2 beta 2的模拟器中还是坏掉了。

我设法通过在if item.active 语句的两个分支中复制列表项来解决它，如下所示：

struct ContentView: View 
    @State var items: [Item] = [
        Item(user: "Daniel",active: false),
        Item(user: "Jack", active: true),
        Item(user: "John", active: true)
    ]

    var body: some View 
        List 
            ForEach(items)  item in
                // work around SwiftUI bug where
                // context menu doesn't update
                if item.active  listItem(for: item) 
                else  listItem(for: item) 
            
        
    

    private func listItem(for item: Item) -> some View 
        VStack 
            Text("\(item.user)")

            HStack 
                Text("Active ? ")
                Text(item.active ? "YES": "NO")
            
        
        .contextMenu 
            Button(item.active ? "Deactivate" : "Activate") 
                if let index = items.firstIndex(where:  $0.id == item.id ) 
                    items[index].active.toggle()
                
            
        
        .id(item.id)