Swift通过appdelegate

Question

尝试通过AppDelegate将子视图添加到UI的前端，但它无法正常工作。我有一个可达性通知程序，它应该在没有互联网连接的情况下从xib添加UIView。

App委托代码：

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")
    }
}

通知会触发，我会在控制台上打印“View is showing”。我试过通过dispatchQueue.main.async来调用它，但这只会导致无限循环崩溃应用程序。

由于

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)
}