有问题与UISplitViewController

Question

我创建了一个字典应用程序，我使用UISplitViewController搜索和选择一个的话，我的应用程序崩溃与此日志：

-[MeaningViewController topViewController]: unrecognized selector sent to instance 0x7f918945bef0

Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[MeaningViewController topViewController]: unrecognized selector sent to instance 0x7f918945bef0'

这里是我的代码： 在ViewController (MasterView)：

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender { 

    [_searchbar resignFirstResponder]; 

    if ([segue.identifier isEqualToString:@"Meaning"]) { 

//MeaningViewController *meaningVC = (MeaningViewController*)[[segue destinationViewController] topViewController]; 

     UINavigationController *navController = (UINavigationController *)segue.destinationViewController; 
     MeaningViewController *meaningVC = (MeaningViewController *)navController.topViewController; 


     NSIndexPath*indexPath = _tableview.indexPathForSelectedRow; 




     AppDelegate *appDelegateClass = (AppDelegate *)[[UIApplication sharedApplication] delegate]; 
     Reader *selectedWord = [[appDelegateClass wordList] objectAtIndex:indexPath.row]; 

     sqlite3 *database; 
     NSString *mean = @""; 

     if (sqlite3_open([appDelegateClass.currentDBPath cStringUsingEncoding:NSUTF8StringEncoding], &database) == SQLITE_OK) { 

      NSString *sql =[NSString stringWithFormat:@"SELECT MEAN from DICM WHERE id = %ld",(long)selectedWord.oid]; 
      sqlite3_stmt *compiledStatement; 

      if(sqlite3_prepare_v2(database, [sql UTF8String] , -1, &compiledStatement, NULL) == SQLITE_OK) { 
       while(sqlite3_step(compiledStatement) == SQLITE_ROW) { 


        const char* f1 = (const char*)sqlite3_column_text(compiledStatement, 0); 
        mean = f1 == NULL ? nil : [[NSString alloc] initWithUTF8String:f1]; 
       }}} 


     readerClass = (Reader *)[appClass.wordList objectAtIndex:indexPath.row]; 

     [meaningVC setGetWord:readerClass.Name]; 
     [meaningVC setGetMeaning:mean]; 
     [meaningVC setGetOid:readerClass.oid]; 

     dbClass=[[DB alloc]init]; 
     [dbClass setViewTime:readerClass.oid]; 

     NSLog(@"mean is %@",readerClass.Name); 
    } 
} 

和在MeaningViewController (Detail)：

- (void)viewDidLoad { 

     [super viewDidLoad]; 
     // Do any additional setup after loading the view. 

     [_word setText:_getWord]; 
     [_mean setText:_getMean]; 
     oid = _getOid; 
    } 

问题带有这一行：

的UINavigationController * navController =（UINavigationController的*）segue.destinationViewController; MeaningViewController * meaningVC =（MeaningViewController *）navController.topViewController;

如果我这个替换上述行：

MeaningViewController *meaningVC = (MeaningViewController*)segue.destinationViewController; 

它工作正常，但它并不能取代详细查看它只是把视图控制器上Master View我怎样才能解决这个问题呢？

这里是AppDelegate代码：

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions { 

UISplitViewController *splitViewController = (UISplitViewController *)self.window.rootViewController; 
    splitViewController.preferredDisplayMode = UISplitViewControllerDisplayModeAllVisible; 
    splitViewController.delegate = self; 
return YES; 

} 


    - (BOOL)splitViewController:(UISplitViewController *)splitViewController collapseSecondaryViewController:(UIViewController *)secondaryViewController ontoPrimaryViewController:(UIViewController *)primaryViewController 
    { 

     return YES; 
    } 

Answer 1

一个问题，我可以看到的是，你的DetailViewController未嵌入自己的UINavigationController。和你的故事板的流动将是这样的：

->SplitVCont--UINavCont1--MasterVController--[O]--UINavCont2--DetailVController 

->SplitVCont--UINavCont2--DetailViewController 

这种情况，在您的prepareForSegue的segue.destinationViewController是保证在所有情况下（折叠/分，并在所有设备）一类的UINavigationController的或者你可以自省以保证安全。

[segue.destinationViewController isKindOfClass:[UINavigationController class]] 

- 在某些情况下DetailViewController将被推到NavigationControllerMasterViewController（区分iPhone 5）

- 在其他情况下DetailViewController将在自己的NavigationController和splitViewController将处理DISPLAYMODE的所有过渡或DeviceOrientation在您的情况下使用其默认行为。