释放细节视图控制器导致内存问题

Question

我有一个基于分割视图控制器的应用程序。在详细信息视图控制器，称之为FirstViewController，当用户按下一个按钮，我更新了新的视图控制器的视图控制器，称之为SecondViewContorller，类似下面：

- (void) buttonPressed:(id)sender { 
    UIViewController <SubstitutableDetailViewController> *detailViewController = nil; 

    SecondViewController *secondVC = [[SecondViewController alloc] initWithNibName:@"SecondViewController" bundle:nil]; 
    ... 
    detailViewController = secondVC; 

    MyAppDelegate *delegate = [[UIApplication sharedApplication] delegate]; 
    UINavigationController *nav = (UINavigationController *)[delegate.splitViewController.viewControllers objectAtIndex: 0]; 
    NSArray *viewControllers = [NSArray arrayWithObjects:nav, detailViewController, nil]; 
    self.splitViewController.viewControllers = viewControllers; 

... 

    [detailViewController release]; 

}

里面的SecondViewController，在某些时候，我们有：

MyAppDelegate *delegate = [[UIApplication sharedApplication] delegate]; 
UINavigationController *nav = (UINavigationController *)[delegate.splitViewController.viewControllers objectAtIndex: 0]; 
NSArray *array = nav.viewControllers; 
// Retrieve the master view controller 
MasterViewController *masterVC = [array objectAtIndex:[array count] - 1]; 
[masterVC selectRowManually:[NSIndexPath indexPathForRow:0 inSection:0]]; 

和selectRowManually里面我再次初始化FirstViewController：

UIViewController <SubstitutableDetailViewController> *detailViewController = nil; 

if (rowNo == 0) { 
     FirstViewController *newDetailViewController = [[FirstViewController alloc] initWithNibName:@"FirstViewController" bundle:nil]; 
     detailViewController = newDetailViewController; 
} 
... 

UINavigationController *nav = (UINavigationController *)[delegate.splitViewController.viewControllers objectAtIndex: 0]; 

// Update the split view controller's view controllers array. 
NSArray *viewControllers = [[NSArray alloc] initWithObjects:nav, detailViewController, nil]; 
delegate.splitViewController.viewControllers = viewControllers; 
[viewControllers release]; 

... 

[detailViewController release]; 

如果我模拟内存将在该时间点警告（在FirstViewController已经再次显示后），我得到一个

-[UIView _invalidateSubviewCache]: message sent to deallocated instance ... 

与

#0  0x012dd057 in ___forwarding___ 
#1  0x012dcf22 in __forwarding_prep_0___ 
#2  0x00b49a55 in -[UIView dealloc] 
#3  0x00bbe52a in -[UIViewController setView:] 
#4  0x00bc0eec in -[UIViewController unloadViewForced:] 
#5  0x00bbcb0a in -[UIViewController unloadViewIfReloadable] 
#6  0x00bbc15b in -[UIViewController didReceiveMemoryWarning] 
#7  0x0006aec7 in -[SecondViewController didReceiveMemoryWarning] at SecondViewController.m:385 
... 

，其中线385堆栈跟踪是

[super didReceiveMemoryWarning]; 

如果在SecondViewController的buttonPressed方法中，我注释了释放该行的位置detailViewContorller，一切正常，但我泄漏内存。如果我以这种方式离开该线路，那么如果出现内存警告，该应用会崩溃。

我该怎么办？

感谢， 米哈伊

Answer 1

我很好奇你的代码的第一个块，你释放你detailViewController代替secondVC？因为您的第二个VC在该方法结束时未发布。您应该在dealloc方法中释放detailViewController，而不是在SplitViewAppDelegate中，因为它是分割视图的根视图的一部分。

干杯，希望它有帮助。