SwiftUI macOS应用：实现窗口层级交互控制及焦点恢复方案问询

需求说明 #

在基于SwiftUI的macOS应用里，要实现以下效果：

• 弹出新窗口时，之前的所有窗口（包括主窗口）都变成不可交互状态，只有最新弹出的子窗口保持活跃
• 窗口层级严格遵循：主窗口 > 子窗口 > 子子窗口 > 更深层级子窗口，只有当前活跃的窗口能被操作
• 关闭子窗口时，打开它的上一级窗口自动恢复控制权；所有子窗口都关闭后，主窗口恢复可交互状态

修改后的完整代码 #

import SwiftUI

struct ContentView: View {
    @State private var mainWindow: NSWindow?
    
    var body: some View {
        VStack {
            Image(systemName: "globe")
                .imageScale(.large)
                .foregroundStyle(.tint)
            Text("Hello, world!")
            
            Button("Open new Window") {
                guard let parentWindow = mainWindow else { return }
                let _ = ChildView(string: "ChildView")
                    .openInWindow(title: "ChildView", sender: self, parentWindow: parentWindow)
            }
        }
        .padding()
        .onAppear {
            // 获取主窗口引用
            mainWindow = NSApplication.shared.windows.first { $0.isMainWindow }
        }
    }
}

extension View {
    @discardableResult
    func openInWindow(title: String, sender: Any?, parentWindow: NSWindow) -> NSWindow {
        let controller = NSHostingController(rootView: self)
        let window = NSWindow(contentViewController: controller)
        
        // 设置窗口层级：子窗口层级比父窗口高一级
        window.level = parentWindow.level + 1
        // 窗口关闭时不自动释放，确保能处理后续逻辑
        window.isReleasedWhenClosed = false
        // 禁用父窗口交互
        parentWindow.isEnabled = false
        
        window.center()
        window.title = title
        window.makeKeyAndOrderFront(sender)
        
        // 设置窗口代理，处理关闭时的父窗口恢复逻辑
        window.delegate = WindowDelegate(parentWindow: parentWindow)
        
        return window
    }
}

// 窗口代理类，处理子窗口关闭时恢复父窗口状态
class WindowDelegate: NSObject, NSWindowDelegate {
    private weak var parentWindow: NSWindow?
    
    init(parentWindow: NSWindow) {
        self.parentWindow = parentWindow
        super.init()
    }
    
    func windowWillClose(_ notification: Notification) {
        guard let parentWindow = parentWindow else { return }
        // 恢复父窗口的交互性
        parentWindow.isEnabled = true
        // 激活父窗口，让它重新获得控制权
        parentWindow.makeKeyAndOrderFront(nil)
    }
}

struct ChildView: View {
    let string: String
    @State private var currentWindow: NSWindow?
    
    var body: some View {
        VStack {
            Text(string).bold()
            
            HStack {
                Button("Open new Window") {
                    guard let parentWindow = currentWindow else { return }
                    let _ = ChildView(string: "Another " + string)
                        .openInWindow(title: "Another " + string, sender: self, parentWindow: parentWindow)
                }

                Button("Dismiss") {
                    currentWindow?.close()
                }
                .buttonStyle(.borderedProminent)
            }
        }
        .frame(width: 400.0, height: 200.0)
        .onAppear {
            // 获取当前子窗口的引用
            currentWindow = NSApplication.shared.keyWindow
        }
    }
}

关键改动说明 #

1. 窗口父子关联：给openInWindow扩展新增parentWindow参数，明确每个子窗口的父窗口，关闭时能精准定位上一级窗口
2. 层级控制：通过window.level = parentWindow.level + 1确保子窗口层级始终高于父窗口，形成主窗口→子窗口→子子窗口的层级链
3. 交互状态切换：打开子窗口时禁用父窗口的交互；子窗口关闭时，通过代理方法windowWillClose恢复父窗口的交互性并激活它
4. 窗口生命周期管理：设置window.isReleasedWhenClosed = false，避免窗口被自动释放，确保代理事件能正常触发
5. 窗口引用获取：在视图onAppear时获取当前窗口的引用，避免依赖NSApplication.shared.keyWindow可能出现的错误

内容的提问来源于stack exchange，提问作者Mango