如何在 SwiftUI 中激活/停用菜单项

Question

我正在尝试在 SwiftUI 应用程序中为 mac os（SwiftUI 应用程序生命周期）创建自定义菜单项。我不太理解以下行为：

在下面的代码中：

import SwiftUI
@main
struct MySQLtoolApp: App {
    @ObservedObject var mysql = MySQL()
    var flags = UtilFlags()
    var selectedDB = "mysql"
    var body: some Scene {
        let mainWindow = WindowGroup(Text("title")) {
            ContentView()
                .environmentObject(mysql)
                .environmentObject(flags)
        }
        .windowStyle(HiddenTitleBarWindowStyle())
        .commands {
            CommandMenu("Tools", content: {
                    Button("Connect...", action: {flags.connectDialogVisibilityFlag = true }).disabled(mysql.connected)
                    Button("Disconnect", action: { mysql.closeBase()
                            mysql.connected = false}).disabled(!mysql.connected)
            })
            CommandGroup(after: .help, addition: {
                Button("Test button", action: {print("Test button pressed")})
                .disabled(!mysql.connected)
            })
        }
        return mainWindow
    }
}

通过 CommandMenu 添加的按钮按预期运行（即根据 'mysql.connected' 的变化值激活和停用）。通过 CommandGroup 添加的按钮在启动时根据 'mysql.connected' 的值正确配置, 但忽略了 'mysql.connected' 的变化并且不改变它的状态。我错过了什么？

我重写了上面的部分以强调这个问题。简而言之：

import SwiftUI

@main
struct MenuTestApp: App {
    @State var active = false
    var body: some Scene {
        WindowGroup {
            ContentView()
        }
        .commands(content: {
            CommandMenu("Tools", content: {
                Button("Normally active", action: {active = !active}).disabled(active)
                Button("Normally inactive", action: {active = !active}).disabled(!active)
            })
            CommandGroup(after: .newItem, addition: {
                Button("Normally active", action: {active = !active}).disabled(active)
                Button("Normally inactive", action: {active = !active}).disabled(!active)
            })
        })
    }
}

通过 CommandMenu 添加的按钮行为正确（根据 'active' 的值激活和停用。通过 CommandGroup 添加的按钮忽略 'active' 的值并保持其初始状态。

Answer 1

我在 Apple dev 中得到了很好的建议。论坛（感谢 OOPer！）。它可能无法解决根本原因（这是 SwiftUI 中的错误吗？），但它提供了一个很好的解决方法。如果我将我的“行为不当”按钮包装到一个视图中并添加它，一切都会按预期工作：

import SwiftUI
@main
struct MySQLtoolApp: App {
    @StateObject var mysql = MySQL()
    var flags = UtilFlags()
    var selectedDB = "mysql"
    var body: some Scene {
        let mainWindow = WindowGroup(Text("title")) {
            ContentView()
                .environmentObject(mysql)
                .environmentObject(flags)
        }
        .windowStyle(HiddenTitleBarWindowStyle())
        .commands {
            CommandMenu("Tools", content: {
                    Button("Connect...", action: {flags.connectDialogVisibilityFlag = true }).disabled(mysql.connected)
                    Button("Disconnect", action: { mysql.closeBase()
                            mysql.connected = false}).disabled(!mysql.connected)
            })
            CommandGroup(after: .newItem, addition: {
                MyButtonsGroup().environmentObject(mysql)
            })
        }
        return mainWindow
    }
}
struct MyButtonsGroup: View {
    @EnvironmentObject var mysql: MySQL
    var body: some View {
        Button("Test button", action: {print("Test button pressed")})
            .disabled(mysql.connected)
    }
}

如何在 SwiftUI 中激活/停用菜单项

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