macOS SwiftUI多窗口专属命令实现：如何让命令仅对应窗口生效？

我尝试为应用的每个窗口添加专属命令（代码示例如下），但即使在两个Window上分别使用.commands修饰符，所有命令始终处于可用状态。请问有没有原生SwiftUI方式，让第一/第二组命令仅分别在第一/第二窗口显示？至少能实现启用/禁用状态切换？

import SwiftUI

@main
struct CommandsTestProjectApp: App {
    @Environment(\.openWindow) private var openWindow

    var body: some Scene {
        // FIRST WINDOW
        Window("First Window", id: "FirstWindow") {
            Text("First Window")
            Button("Open Second Window") {
                openWindow.callAsFunction(id: "SecondWindow")
            }
        }
        .commands {
            FirstCommands()
        }

        // SECOND WINDOW
        Window("Second Window", id: "SecondWindow") {
            Text("Second Window")
        }
        .commands {
            SecondCommands()
        }
    }
}

struct FirstCommands: Commands {
    var body: some Commands {
        CommandGroup(after: .newItem) {
            Button("First button") {

            }
        }
    }
}

struct SecondCommands: Commands {
    var body: some Commands {
        CommandGroup(after: .newItem) {
            Button("Second button") {

            }
        }
    }
}

核心思路是追踪当前激活的窗口ID，以此为依据控制命令的显示或启用状态。

1. 实现命令仅对应窗口显示 #

通过创建共享状态对象管理当前激活窗口，在命令组中根据状态判断是否渲染按钮：

import SwiftUI

// 管理当前激活窗口的状态对象
class ActiveWindowManager: ObservableObject {
    @Published var activeWindowID: String?
}

@main
struct CommandsTestProjectApp: App {
    @Environment(\.openWindow) private var openWindow
    // 创建全局共享的状态对象
    @StateObject private var windowManager = ActiveWindowManager()

    var body: some Scene {
        Window("First Window", id: "FirstWindow") {
            Text("First Window")
            Button("Open Second Window") {
                openWindow(id: "SecondWindow")
            }
        }
        // 监听窗口激活状态，更新当前窗口ID
        .onChange(of: ScenePhase.active) { newPhase in
            if newPhase == .active {
                windowManager.activeWindowID = "FirstWindow"
            }
        }
        .commands {
            FirstCommands(windowManager: windowManager)
        }

        Window("Second Window", id: "SecondWindow") {
            Text("Second Window")
        }
        .onChange(of: ScenePhase.active) { newPhase in
            if newPhase == .active {
                windowManager.activeWindowID = "SecondWindow"
            }
        }
        .commands {
            SecondCommands(windowManager: windowManager)
        }
    }
}

struct FirstCommands: Commands {
    @ObservedObject var windowManager: ActiveWindowManager

    var body: some Commands {
        CommandGroup(after: .newItem) {
            // 仅当前窗口激活时显示按钮
            if windowManager.activeWindowID == "FirstWindow" {
                Button("First button") {
                    // 执行命令逻辑
                }
            }
        }
    }
}

struct SecondCommands: Commands {
    @ObservedObject var windowManager: ActiveWindowManager

    var body: some Commands {
        CommandGroup(after: .newItem) {
            if windowManager.activeWindowID == "SecondWindow" {
                Button("Second button") {
                    // 执行命令逻辑
                }
            }
        }
    }
}

2. 实现命令启用/禁用切换 #

如果不想隐藏按钮，仅在非对应窗口时禁用，用disabled修饰符替代条件判断即可：

// 以FirstCommands为例，SecondCommands逻辑一致
struct FirstCommands: Commands {
    @ObservedObject var windowManager: ActiveWindowManager

    var body: some Commands {
        CommandGroup(after: .newItem) {
            Button("First button") {
                // 执行命令逻辑
            }
            // 当前窗口非目标窗口时禁用按钮
            .disabled(windowManager.activeWindowID != "FirstWindow")
        }
    }
}

注意事项 #

• 窗口激活状态依赖ScenePhase监听，窗口从后台切回前台时会自动更新状态。
• 若需支持更多窗口，只需扩展activeWindowID的判断逻辑即可。

内容的提问来源于stack exchange，提问作者viedev