swift - Hook 以退出应用程序事件并显示警报

Question

当用户通过单击 x 按钮退出应用程序时，我需要显示一个警告框。我如何 Hook 到应用程序的退出事件并通过以下方式显示警告或 View Controller 一个 segue

performSegue(withIdentifier: "segue", sender: nil)

请指教..

Answer 1

我知道您想使用 segue 来执行此操作，因为它们非常方便，但是无法在 Storyboard中从应用程序委托(delegate)事件(如“applicationWillResignActive”(继续背景)或“applicationWillBecomeActive”(再次成为前台)。

执行此操作的正确方法是通过警报。并且您可能希望在 applicationShouldTerminate 中执行此操作，因为您可能希望 A) 如果您有充分的理由暂时不退出，则能够中止退出或 B) 给用户一个选择是否真的戒掉。

这是它在 swift 4 中的样子:

var licenseWindowController : LicenseWindowController?

func dialogOKCancel(question: String, text: String) -> Bool {
    let alert = NSAlert()
    alert.messageText = question
    alert.informativeText = text
    alert.alertStyle = .warning
    alert.addButton(withTitle: "OK")
    alert.addButton(withTitle: "Cancel")
    return alert.runModal() == .alertFirstButtonReturn
}

func applicationShouldTerminate(_ sender: NSApplication) -> NSApplication.TerminateReply {

    let answer = dialogOKCancel(question: "Ok?", text: "Should we really quit?")
    if answer == true
    {
        return .terminateNow
    } else {

func applicationShouldTerminate(_ sender: NSApplication) -> NSApplication.TerminateReply {

    let answer = dialogOKCancel(question: "Ok?", text: "Should we really quit?")
    if answer == true
    {

        return .terminateNow

    } else {

        // to bring up a window from your storyboard...
        let mainStoryboard = NSStoryboard.init(name: NSStoryboard.Name(rawValue: "Main"), bundle: nil)
        self.licenseWindowController = mainStoryboard.instantiateController(withIdentifier: NSStoryboard.SceneIdentifier(rawValue: "LicenseWindowController")) as? LicenseWindowController
        if let actualLicenseWC = self.licenseWindowController
        {
            actualLicenseWC.showWindow(self)
        }

        return .terminateCancel
    }
}

swift 3

var licenseWindowController : LicenseWindowController?

func dialogOKCancel(question: String, text: String) -> Bool {
    let alert = NSAlert()
    alert.messageText = question
    alert.informativeText = text
    alert.alertStyle = .warning
    alert.addButton(withTitle: "OK")
    alert.addButton(withTitle: "Cancel")
    return alert.runModal() == NSAlertFirstButtonReturn
}

func applicationShouldTerminate(_ sender: NSApplication) -> NSApplicationTerminateReply {

    let answer = dialogOKCancel(question: "Ok?", text: "Should we really quit?")
    if answer == true
    {
        return .terminateNow
    } else {
        let mainStoryboard = NSStoryboard.init(name: "Main", bundle: nil)
        self.licenseWindowController = mainStoryboard.instantiateController(withIdentifier: "LicenseWindowController") as? LicenseWindowController
        if let actualLicenseWC = self.licenseWindowController
        {
            actualLicenseWC.showWindow(self)
        }

        return .terminateCancel
    }
}