在呈现另一个视图控制器之前关闭视图控制器

Question

我正在使用 MZFormSheetPresentationController 显示一个对话框，要求用户输入密码，如下图所示： 用户点击OK后会出现另一个视图控制器，如下图所示： 但是在关闭新的视图控制器后，旧的视图控制器仍然存在在我的情况下应用这样的答案我的代码我正在使用什么：

- (IBAction)okButtonTouchDown:(id)sender {

   // UIStoryboard *storyboard = self.storyboard;
  //  UINavigationController *nav = [storyboard instantiateViewControllerWithIdentifier:@"myprofile"];
   // [self presentViewController:nav animated:YES completion:^{

       // [self dismissViewControllerAnimated:YES completion:nil]; // here the self point to the new view controller not to the old one //




//[self dismissViewControllerAnimated:YES completion:^{


      //  UINavigationController *nav = [storyboard instantiateViewControllerWithIdentifier:@"myprofile"];
     //   [self presentViewController:nav animated:YES completion:^{



        //}];


    // }];


   //}];



    __weak EditProfileViewController *aBlockSelf = self;
UIStoryboard *storyboard = self.storyboard;
UINavigationController *nav = [storyboard instantiateViewControllerWithIdentifier:@"myprofile"];
 [self   presentViewController:nav animated:YES completion:^{
    [[aBlockSelf presentingViewController] dismissViewControllerAnimated:YES completion:nil];
    }];

  }


// i try this solution but the new view controller presented and after some time dismissed //

即使我尝试在完成后关闭viewcontroller，我也会遇到此错误警告：尝试在其视图上显示不在窗口层次结构中的视图！

那么有没有办法不使用委托和协议方法来解决这个问题？

Answer 1

将此作为扩展添加到您的 AppDelegate

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

}

然后这样做

self.dismissViewControllerAnimated(true, completion: {
        let vc = self.storyboard?.instantiateViewControllerWithIdentifier("yourIdentifierHere")
        UIApplication.topViewController()?.presentViewController(vc!, animated: true, completion: nil)
    })

目标-C

- (UIViewController *)topViewController{
    return [self topViewController:[UIApplication sharedApplication].keyWindow.rootViewController];
}
- (UIViewController *)topViewController:(UIViewController *)rootViewController {
    if ([rootViewController isKindOfClass:[UINavigationController class]]) {
        UINavigationController *navigationController = (UINavigationController *)rootViewController;
        return [self topViewController:[navigationController.viewControllers lastObject]];   
    }
    if ([rootViewController isKindOfClass:[UITabBarController class]]) {
        UITabBarController *tabController = (UITabBarController *)rootViewController;
        return [self topViewController:tabController.selectedViewController];
    }
    if (rootViewController.presentedViewController) {
        return [self topViewController:rootViewController];
    }
    return rootViewController;
}