objective-c - 后台应用程序 : NSAlert before shutdown

Question

我想要一个状态栏应用程序，它会在系统关闭/重启之前显示一个NSAlert。 (只是一个 NSStatusItem，没有窗口。)

它检测到关机并显示警报，但在用户可以与警报交互之前，应用程序终止然后系统关闭。

有没有办法强制系统在系统关闭之前等待警报完成？

编辑:如果应用程序显示在 Dock 中，代码确实有效，但如果它是 NSApplicationActivationPolicy.Accessory 或 UI 元素<，则代码无效。我试图在它退出之前将其恢复到 Dock，但在它再次弹出之前它已被终止。

这是代码示例:

func receivedPowerOffNotification(notification: NSNotification) {

        let myAlert: NSAlert = NSAlert()
        myAlert.alertStyle = NSAlertStyle.CriticalAlertStyle
        myAlert.messageText = "Title"
        myAlert.informativeText = "Please wait for this alert"
        myAlert.addButtonWithTitle("OK")
        myAlert.addButtonWithTitle("Not OK")
        let response = myAlert.runModal()
        if response != NSModalResponseOK {
            // Do something here before shutdown the system.
        }
    }
    NSApplication.sharedApplication().replyToApplicationShouldTerminate(true)
}

func applicationShouldTerminate(sender: NSApplication) -> NSApplicationTerminateReply {
    // userQuit = if the termination was caused by the Quit menu.
    return userQuit ? NSApplicationTerminateReply.TerminateNow : NSApplicationTerminateReply.TerminateLater
}

Answer 1

好的，在与 Apple 的开发人员技术支持 (DTS) 来回发送电子邮件后，简短的回答是这是不可能的(对于 Developer Technical Support strong>LSUIElement/Agent 以捕获关闭/重启 进程):

引自 Apple 员工:

The rules change in AppKit for apps that are user-agent based. They are designed not to interact with the user, even through our documentation states you can add windows. Since your app has an NSStatusItem, which constitutes a UI, it should not be user-agent based. You are interacting with the user in this case.

我确实问过是否有任何“内部”方式。答案仍然是否定的。