MacOS App无法将SwiftUI视图设为根视图控制器，窗口无内容如何解决

• 你实例化NSWindowController后没有调用showWindow()方法触发窗口渲染
• 没有将NSWindowController实例声明为AppDelegate的成员变量持有，函数执行结束后实例会被ARC自动释放，窗口自然无法展示

直接修改你的AppDelegate代码即可，ContentView无需调整：

class AppDelegate: NSObject, NSApplicationDelegate {
    // 声明为成员变量持有，避免被自动释放
    var mainWindowController: NSWindowController?
    let contentView = NSHostingController(rootView: ContentView())

    func applicationDidFinishLaunching(_ aNotification: Notification) {
        let storyBoard = NSStoryboard(name: NSStoryboard.Name("Main"), bundle: Bundle.main)
        mainWindowController = storyBoard.instantiateController(withIdentifier: "Main Window") as? NSWindowController
        guard let mainWindowController = mainWindowController else { return }
        mainWindowController.contentViewController = contentView
        // 调用方法展示窗口
        mainWindowController.showWindow(nil)
    }
}

如果你不想维护Storyboard配置，可以直接用代码初始化窗口，实现更简洁：

class AppDelegate: NSObject, NSApplicationDelegate {
    var mainWindow: NSWindow?

    func applicationDidFinishLaunching(_ aNotification: Notification) {
        // 直接创建窗口实例
        mainWindow = NSWindow(
            contentRect: NSRect(x: 0, y: 0, width: 600, height: 400),
            styleMask: [.titled, .closable, .miniaturizable, .resizable],
            backing: .buffered,
            defer: false
        )
        mainWindow?.center()
        // 直接设置SwiftUI视图为窗口内容
        mainWindow?.contentView = NSHostingView(rootView: ContentView())
        mainWindow?.makeKeyAndOrderFront(nil)
    }
}

内容的提问来源于stack exchange，提问作者user4150758