UIViewController 关闭时不接收 dealloc 或 viewDidUnload

Question

更新：我在调试中犯了一个错误 - 这个问题无关紧要 - 请参阅下面的评论。

注意：我正在使用自动引用计数

当我的应用程序启动时 - 我在 UINavigationController 和 presentViewController:animated:completion 中显示了一个视图控制器。该视图控制器将第二个视图控制器加载到导航堆栈上。第二个视图控制器使用[self.presentingViewController dismissViewControllerAnimated:YES completion:nil] 关闭自己。我的问题是，在第一个视图控制器中既没有调用 dealloc 也没有调用 viewDidUnload。但是，使用工具，我可以看到一旦呈现的视图控制器被解除，视图控制器就不再被分配。呈现第一个视图控制器的代码是

- (void)viewDidAppear:(BOOL)animated                                                                                                                                                                                                         
{                                                                                                                                                                                                                                            
    [super viewDidAppear:animated];                                                                                                                                                                                                          

    //  check if our context has any accounts                                                                                                                                                                                                
    if( [self.accounts count] == 0 )                                                                                                                                                                                    
    {                                                                                                                                                                                                                                        
        //  Display the Add Account View Controller                                                                                                                                                                                          
        MySettingsViewController *settingsVC = [[MySettingsViewController alloc] initWithNibName:@"MySettingsViewController" bundle:nil];                                                                                                 
        settingsVC.appContext = self.appContext;                                                                                                                                                                                             

        UINavigationController *navVC = [[UINavigationController alloc] initWithRootViewController:settingsVC];                                                                                                                              
        navVC.modalTransitionStyle = UIModalTransitionStyleCrossDissolve;                                                                                                                                                                    

        if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPhone)                                                                                                                                                      
        {                                                                                                                                                                                                                                    
            //  Display the Add Account View Controller                                                                                                                                                                                      
        }                                                                                                                                                                                                                                    
        else                                                                                                                                                                                                                                 
        {                                                                                                                                                                                                                                    
            navVC.modalPresentationStyle = UIModalPresentationFormSheet;                                                                                                                                                                     
        }                                                                                                                                                                                                                                    

       [self presentViewController:navVC animated:YES completion:nil];                                                                                                                                                                       
    }                                                                                                                                                                                                                                        
}            

所以，我没有任何应该保留的对 settingsVC 的引用，但我不知道为什么我的 dealloc 没有被调用。任何帮助都会很棒。

Answer 1

他们没有被调用，因为你没有正确地释放你的视图控制器。

您将settingsVC 和navVC 分配给alloc，从而获得对两者的引用，您必须稍后发布而您没有这样做。

你可以这样做：

- (void)viewDidAppear:(BOOL)animated                                                                                                                                                                                                         
{                                                                                                                                                                                                                                            
    [super viewDidAppear:animated];                                                                                                                                                                                                          

    //  check if our context has any accounts                                                                                                                                                                                                
    if( [self.accounts count] == 0 )                                                                                                                                                                                    
    {                                                                                                                                                                                                                                        
        //  Display the Add Account View Controller                                                                                                                                                                                          
        MySettingsViewController *settingsVC = [[MySettingsViewController alloc] initWithNibName:@"MySettingsViewController" bundle:nil];                                                                                                 
        settingsVC.appContext = self.appContext;                                                                                                                                                                                             

        UINavigationController *navVC = [[UINavigationController alloc] initWithRootViewController:settingsVC];
        navVC.modalTransitionStyle = UIModalTransitionStyleCrossDissolve;                                                                                                                                                                    

        // At this points, "settingsVC" is additionally retained by the navigation controller,
        // so we can release it now.
        [settingsVC release];

        if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPhone)                                                                                                                                                      
        {                                                                                                                                                                                                                                    
            //  Display the Add Account View Controller                                                                                                                                                                                      
        }                                                                                                                                                                                                                                    
        else                                                                                                                                                                                                                                 
        {                                                                                                                                                                                                                                    
            navVC.modalPresentationStyle = UIModalPresentationFormSheet;                                                                                                                                                                     
        }                                                                                                                                                                                                                                    

        [self presentViewController:navVC animated:YES completion:nil];

        // At this point "navVC" is retained by UIKit, so we can release it as well.
        [navVC release];
    }                                                                                                                                                                                                                                        
}           

另一种选择是立即使用autorelease。