应用程序委托(delegate)中的 iOS 弹出消息？

Question

我尝试在我的应用委托(delegate)中创建一个弹出式警告消息，但它根本没有显示。该程序是用 Swift 4 编写的。

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
    let alert = UIAlertController(title: "title", message: "message", preferredStyle: UIAlertControllerStyle.alert)
    alert.addAction(UIAlertAction(title: "OK", style: UIAlertActionStyle.default, handler: nil))
    self.window?.rootViewController?.present(alert, animated: true, completion: nil)
}

Answer 1

根据 the documentation for didFinishLaunching :

Tells the delegate that the launch process is almost done and the app is almost ready to run.

所以我认为您不能在 didFinishLaunchingWithOptions 中显示警报。

尝试将您的代码移动到 applicationDidBecomeActive。