在SwiftUI中打开关闭的NSWindow会使应用程序崩溃

Question

我在SwiftUI Mac应用程序中有一个“偏好设置”窗口。通过单击“首选项...”菜单项打开该窗口。窗口在第一次打开时应显示。但是，如果关闭“首选项”窗口，然后从菜单项中重新打开它，则应用程序将崩溃。如何正确关闭并重新打开“首选项”窗口而不会导致应用程序崩溃？

AppDelegate.swift

import Cocoa
import SwiftUI

@NSApplicationMain
class AppDelegate: NSObject, NSApplicationDelegate {

    var window: NSWindow!
    var prefsWindow: NSWindow!

    @IBAction func openPrefsWindow(_ sender: NSMenuItem) {

        let prefsView = PreferencesView(

        prefsWindow = NSWindow(
            contentRect: NSRect(x: 0, y: 0, width: 480, height: 300),
            styleMask: [.titled, .closable],
            backing: .buffered,
            defer: false)
        prefsWindow.center()
        prefsWindow.title = "Preferences"
        prefsWindow.setFrameAutosaveName("Preferences Window")
        prefsWindow.contentView = NSHostingView(rootView: prefsView)
        prefsWindow.makeKeyAndOrderFront(nil)
    }

    func applicationDidFinishLaunching(_ aNotification: Notification) {

        let contentView = ContentView()

        window = NSWindow(
            contentRect: NSRect(x: 0, y: 0, width: 480, height: 300),
            styleMask: [.titled, .closable, .miniaturizable, .resizable, .fullSizeContentView],
            backing: .buffered,
            defer: false)
        window.center()
        window.setFrameAutosaveName("Main Window")
        window.contentView = NSHostingView(rootView: contentView)
        window.makeKeyAndOrderFront(nil)
    }
}

PreferencesView.swift

import SwiftUI

struct PreferencesView: View {
    var body: some View {
        Text("Preferences Window")
            .frame(width: 400, height: 200)
    }
}

struct PreferencesView_Previews: PreviewProvider {
    static var previews: some View {
        PreferencesView()
    }
}

Answer 1

与SwiftUI无关。您必须像这样为prefesWindow设置一些内容：

  .....
       prefsWindow.contentView = NSHostingView(rootView: prefsView)
       prefsWindow.makeKeyAndOrderFront(nil)
       prefsWindow.isReleasedWhenClosed = false

 }

请参见上面的最后一行。