iOS 应用程序试图在目标 <UINavigationController: 上推送一个 nil 视图控制器：

Question

XMPP 使用 tableview 我正在尝试使用特定用户名转到下一个视图控制器。所以为此我已经正确实现了 UItablevie 的didselectrowatIndexpath。但是当我点击用户名时会出现这样的错误。

应用程序试图在目标上推送一个 nil 视图控制器。

"。 2015-06-04 14:22:51.063

我已经像这样在 appdelegate.m 中声明了故事板。

 - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
      ChatViewController *ChatViewController1 = [[ChatViewController alloc]init];
self.storyboard = [UIStoryboard storyboardWithName:@"Main" bundle:nil];


return YES;
}

这是我的 tableview 的 Delegate 方法。

 - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
 {
[self.tblvwbuddy deselectRowAtIndexPath:indexPath animated:YES];
XMPPUserCoreDataStorageObject *user = nil;
user = [[self fetchedResultsController] objectAtIndexPath:indexPath];

ChathistryViewController *chathistory1 = [[ChathistryViewController alloc] init]; // or initWith...
chathistory1 = [appdelegate.storyboard instantiateViewControllerWithIdentifier:@"ChathistryViewController"];//My next view controller's name
     chathistory1.chatUserObject = user;

      chathistory1.hidesBottomBarWhenPushed = YES;

chathistory1.self.tabBarController.navigationItem.title = user.displayName;

[self.tabBarController.navigationController pushViewController:chathistory1 animated:YES];

}

我缺少什么？还是我错了？

Answer 1

试试这个：

 UITabBarController *vc = [self.storyboard instantiateViewControllerWithIdentifier:@"main"];
        NSArray *listViewController=vc.viewControllers;
        vc.selectedViewController=[listViewController objectAtIndex:1];
        [self presentViewController:vc animated:YES completion:nil];

ps.... listViewController objectAtIndex: 1

Answer 2

我猜你的故事板没有正确初始化，因为你遇到了错误。

不是在委托类中创建故事板对象，而是遵循以下方法来检索故事板对象。

UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"Main" bundle:[NSBundle mainBundle]];

让我知道它是否有效。

Answer 3

编辑

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
     ChatViewController *ChatViewController1 = [[ChatViewController alloc]init];
     self.storyboard = [UIStoryboard storyboardWithName:@"Main" bundle:nil];

     //HOW DID YOU DECLARE the rootViewController?
     /*
     you CANNOT do this: 
     self.window.rootViewController = ChatViewController1;
     */

     //you MUST have declared it like: right? becuase your are using navigationController
     UINavigationController *navigationView = self.storyboard instantiateViewControllerWithIdentifier:@"naviController"/*Storyboard ID*/];
     self.window.rootViewController = navigationView;

     //Manually setting navigationController rootViewController, example your rootViewController is ChatViewController
     UIViewController = self.storyboard instantiateViewControllerWithIdentifier:@"ChatViewController"/*Storyboard ID*/];
     [navigationView setViewControllers:UIViewController animated:NO];

     return YES;
}

结束编辑

chathistory1 = [appdelegate.storyboard instantiateViewControllerWithIdentifier:@"ChathistryViewController"];troller

您必须设置自定义类，在您的情况下：(ChathistryViewController)

并确保您的 ChathistryViewController 作为 Storyboard ID 存在于您的 Storyboard 中

来自您的代码：

chathistory1 = [appdelegate.storyboard instantiateViewControllerWithIdentifier:@"ChathistryViewController"];

我认为这样分配它会更好：

//From your code [[ChathistryViewController alloc] init]; will be use less
ChathistryViewController *chathistory1 = [[ChathistryViewController alloc] init]; 
chathistory1 = [appdelegate.storyboard instantiateViewControllerWithIdentifier:@"ChathistryViewController"];

更好的分配：

ChathistryViewController *chathistory1 = [appdelegate.storyboard instantiateViewControllerWithIdentifier:@"ChathistryViewController"];

另一个是你的[appdelegate.storyboard instantiateViewControllerWithIdentifier:];

你在哪里声明了appdelegate？

您可以通过以下方式访问 AppDelegates 属性：

ChathistryViewController *chathistory1 = [[UIApplication sharedApplication].storyboard instantiateViewControllerWithIdentifier:@"ChathistryViewController"];