Question

从非UIViewController类（可可类的接口类）到会话vc获取值（我正在使用通知中心）后，我试图显示会话vc。

现在是第一次，我的会话vc在我当前的顶级vc上正确显示。但是第二次之后，我只得到白屏。但是会话vc中具有的api调用值仍在运行。我可以在控制台中看到。

这是我的代码：

TopView.swift：

import UIKit
class TopView:NSObject{
    class func topViewController(base: UIViewController? = UIApplication.shared.keyWindow?.rootViewController) -> UIViewController? {
        if let nav = base as? UINavigationController {
            return topViewController(base: nav.visibleViewController)
        }
        if let tab = base as? UITabBarController {
            if let selected = tab.selectedViewController {
                return topViewController(base: selected)
            }
        }
        if let presented = base?.presentedViewController {
            return topViewController(base: presented)
        }
        return base
    }

}

Appdelegate：

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {

 NotificationCenter.default.addObserver(self, selector: #selector(AppDelegate.onOver(notification:)), name: NSNotification.Name(rawValue: "openBoard"), object: nil);


}

 @objc func onOver(notification: NSNotification)
    {
   if let score = notification.object as? NSDictionary
        {
            DispatchQueue.background(delay: 0.1000, completion:{
             DispatchQueue.main.async {
                    let storyBoard = UIStoryboard.init(name: "Trai", bundle: nil);
                    if let sessionvc = storyBoard.instantiateViewController(withIdentifier:
                        "sessionvc") as? sessionvc{

                        if let navController = TopView.topViewController()?.navigationController as? UINavigationController{
                            TopView.topViewController()?.navigationController?.pushViewController(sessionvc, animated: true)
                        }else{
                            TopView.topViewController()?.present(sessionvc, animated: true)
                        }
                }

            }
        })
        }
    }

无论如何，我添加了断点。它总是会出现在下面这行：

TopView.topViewController()?.present(sessionvc, animated: true)

第一次，它工作正常，第二次只出现白屏。不确定是否需要从顶部或当前vc中删除任何vc。

任何解决方案都会有所帮助。

谢谢

已更新：

@objc func onOver(notification: NSNotification)
{
    if let score = notification.object as? NSDictionary
    {
                let storyBoard = UIStoryboard.init(name: "Trai", bundle: nil);
                if let sessionvc = storyBoard.instantiateViewController(withIdentifier:
                    "sessionvc") as? sessionvc{

                    if let navController = TopView.topViewController()?.navigationController as? UINavigationController{
                        TopView.topViewController()?.navigationController?.pushViewController(sessionvc, animated: true)
                    }else{
                        TopView.topViewController()?.present(sessionvc, animated: true)
                    }
                }

    }

第二次在当前vc中显示vc后获得白屏

0 个答案: