iphone - popToRootViewControllerAnimated 后内存未释放

Question

我在我的应用程序中使用 navigationController。在我推送并弹出 View Controller 3 次后，我的应用程序因内存不足而崩溃。这是我的代码。

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
        self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
        HomePageVC *homePage = [[ViewController alloc] homePage = [[ViewController alloc] initWithNibName:@"MainView-iPad" bundle:nil];
        navigationController = [[UINavigationController alloc] initWithRootViewController:homePage];
        self.window.rootViewController = navigationController;
        [self.window makeKeyAndVisible];
        return YES;
}

当用户按下按钮时，我将他发送到另一个 View Controller 。

 -(IBAction)showMap:(id)sender
 {
    MapViewController *mapViewController = Nil;
    mapViewController = [[MapViewController alloc] initWithNibName:@"MapView-iPad" bundle:nil];
    AppDelegate *appDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];
    [appDelegate.navigationController pushViewController:mapViewController animated:YES];
 }

当他想回到 rootView Controller 时，我做

-(IBAction)goBack:(id)sender
{
    AppDelegate *appDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];
    [appDelegate.navigationController popToRootViewControllerAnimated:YES];
}

现在，在执行了几次之后，didReceiveLowMemory 逐渐被调用并且应用程序崩溃了。

为了进一步调试，我在循环中打印了内存使用情况。

-(void) report_memory {
    struct task_basic_info info;
    mach_msg_type_number_t sizeM = sizeof(info);
    kern_return_t kerr = task_info(mach_task_self(),
                               TASK_BASIC_INFO,
                               (task_info_t)&info,
                               &sizeM);
    if( kerr == KERN_SUCCESS ) {
        NSLog(@"Memory usage: %.4lf MB", info.resident_size/1000000.0);
    } else {
        NSLog(@"Error with task_info(): %s", mach_error_string(kerr));
    }
}

输出是

When the app Launches    : Memory usage: 137.8263 MB
After showMap First Time : Memory usage: 206.2172 MB
Gone Back Home           : Memory usage: 223.6580 MB   ==> MapVC didn't release

After showMap Second Time: Memory usage: 227.2172 MB
Press Go Back Home       : Memory usage: 250.2172 MB   ==> MapVC didn't release

After showMap Third Time : App Crashes

我的lowMemory写成

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    NSLog(@"Got Low Memory From %@",[self class]);
}

更令人惊讶的是，我从 HomePageVC 和 MapVC 收到了低内存警告。如果我已经 pooped 了 MapVC，我是如何从它那里接收到 lowMemory 的？为什么 MapVC 消耗的内存没有被释放？我正在使用 ARC。

Answer 1

我在我的代码(使用 ARC)中遇到了同样的问题，我的 UIViewController 在调用 popToRootViewControllerAnimated 后没有被释放:

我的错误原因是 UIViewController 中的 NSTimer。我试图使 dealloc 中的计时器无效，但因为我的 NSTimer 使用的是 target:self(即保留指向我的 UIViewController 的指针)dealloc 从未被调用。

为解决此问题，我使 viewWillDisappear 中的计时器无效。