Swift 通过 appdelegate 将视图添加到前面

Question

尝试通过 AppDelegate 将子视图添加到 UI 的前面，但它不起作用。我有一个可达性通知器，当没有互联网连接时，它应该从 xib 添加 UIView。

应用代理代码：

func reachabilityChanged(note: Notification) {
    let reachability = note.object as! Reachability
    if !reachability.isReachable {
        print("APP: Network reachable")
        if networkErrorView != nil {
            networkErrorView.removeFromSuperview()
        }
    } else {
        print("ERROR: Network not reachable")
        networkErrorView = NetworkErrorView(frame: CGRect(x: 30, y: self.window!.frame.height / 4, width: self.window!.frame.width - 60, height: self.window!.frame.height / 2))
        UIApplication.shared.keyWindow?.addSubview(networkErrorView)
        UIApplication.shared.keyWindow?.bringSubview(toFront: networkErrorView)
        print("View is showing")
    }
}

通知确实触发了，并且我确实将“视图正在显示”打印到控制台。我尝试通过dispatchQueue.main.async 调用它，但这只会导致应用程序崩溃的无限循环。

谢谢

Answer 1

private func dismissOfflineScreen() {
    if let navigationVC = self.window?.rootViewController?.presentedViewController as? UINavigationController, navigationVC.viewControllers.first is OfflineViewController {
        navigationVC.dismiss(animated: true, completion: nil)
    }
}

private func presentOfflineScreen() {
    let navigationVC = UINavigationController(rootViewController: OfflineViewController())
    navigationVC.view.backgroundColor = UIColor.clear
    navigationVC.modalPresentationStyle = UIModalPresentationStyle.overFullScreen
    self.window?.rootViewController?.present(navigationVC, animated: true)
}

Answer 2

在 else 中尝试访问当前的 viewController ：

if let currentViewController = self.window?.rootViewController {
    let screenSize = UIScreen.main.bounds
    networkErrorView = NetworkErrorView(frame: CGRect(x: 30, y: (screenSize.height / 4), width: (screenSize.width - 60), height: (screenSize.height / 2)))
    currentViewController.view.addSubview(networkErrorView)
    currentViewController.view.bringSubview(toFront: networkErrorView)
}