iphone - 有任何可达性专家吗？

Question

在将Reachability .h和.m文件合并到其中以检查Internet连接之前，我的应用程序运行良好。尽管大部分情况下一切仍然运行正常(所有网页均正确加载，并且当我有意关闭机场进行测试时，可达性很好地捕获了它)-我现在确实在奇怪的时候遇到了莫名其妙的崩溃，令人恐惧的“Exc-Bad-Access”错误...
我运行仪器并找到了僵尸-参见屏幕抓图:

查看“RefCt”列，您可以看到它达到15-我已经看到它超过20!
在“负责 call 者”列(最右侧)中，我看到了各种我不认识的方法-以及我当然没有启动的 call 者-我假设它们在运行期间由系统内部调用-时间？

无论哪种方式，我都非常仔细地遵循了Apple的可达性代码和说明，以及来自这个排名很高的stackoverflow线程的提示:
How to check for an active Internet connection on iOS or OSX?

但是我仍然遇到这些莫名其妙的崩溃。

谁能提供任何建议？

这是代码:

#import "Reachability.h"


-(void) viewWillAppear:(BOOL)animated
{
   // check for internet connection
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(checkNetworkStatus:) name:kReachabilityChangedNotification object:nil];

internetReachable = [[Reachability reachabilityForInternetConnection] retain];
[internetReachable startNotifier];

// check if a pathway to a random host exists
hostReachable = [[Reachability reachabilityWithHostName: @"www.apple.com"] retain];
[hostReachable startNotifier];

// now patiently wait for the notification
}



-(void) viewDidLoad {

    url = [NSURL URLWithString: @"http://www.google.com"];
    NSURLRequest *req = [NSURLRequest requestWithURL: url];
    [webPageView loadRequest:req];
    [super viewDidLoad];
}



-(void) checkNetworkStatus:(NSNotification *)notice
{
        // called after network status changes

    NetworkStatus internetStatus = [internetReachable currentReachabilityStatus];

    switch (internetStatus) 
    {
        case NotReachable:
        {
            [self displayMessageWithTitle:@"ERROR"
                               andMessage:@"Unable To Connect to Internet"
                              andOKButton:@"OK"];
            [self dismissModalViewControllerAnimated:YES];
            break;

        }
        case ReachableViaWiFi:
        {
            NSLog(@"The internet is working via WIFI.");

            break;

        }
        case ReachableViaWWAN:
        {
            NSLog(@"The internet is working via WWAN.");

            break;

        }
    }

    NetworkStatus hostStatus = [hostReachable currentReachabilityStatus];
    switch (hostStatus)
    {
        case NotReachable:
        {
            // NSLog(@"A gateway to the host server is down.");

            [self displayMessageWithTitle:@"ERROR"
                               andMessage:@"Host Not Reachable"
                              andOKButton:@"OK"];
            [self dismissModalViewControllerAnimated:YES];
            break;

        }

        case ReachableViaWiFi:
        {
            NSLog(@"A gateway to the host server is working via WIFI.");

            break;

        }

        case ReachableViaWWAN:
        {
            NSLog(@"A gateway to the host server is working via WWAN.");

            break;

        }
    }
}



- (void)webViewDidStartLoad:(UIWebView *)webView {
    [activityIndicator startAnimating];
}


- (void)webViewDidFinishLoad:(UIWebView *)webView {
    [activityIndicator stopAnimating];
}


// Since this ViewController is presented Modally, this method removes it 
// via a button click:
-(IBAction) dismissWebTixView:(id)sender {
    [self dismissModalViewControllerAnimated:YES];
}




-(void) viewWillDisappear:(BOOL)animated {
    NSLog(@"In webForTix's 'viewWillDisappear' method....");
    [[NSNotificationCenter defaultCenter] removeObserver:self
name:kReachabilityChangedNotification
                                              object:nil];
}


// Was told it might be good to put "removeObserver" here and not in viewWillDisappear
// well neither worked - the App still crashes....
- (void)dealloc
{
    //NSLog(@"In webForTix's dealloc method....");
//    [[NSNotificationCenter defaultCenter] removeObserver:self
//                                                        name:kReachabilityChangedNotification
//                                                  object:nil];
NSLog(@"In webForTix's dealloc method - removedObserver...");
[super dealloc];

}

Answer 1

您必须仔细平衡对addObserver和removeObserver的调用。

如果在vieWillAppear中添加通知的观察者，则需要在viewWillDisappear中将其删除。

如果您两次添加观察者，则对于同一通知您将被调用两次，并且必须调用两次removeObserver才能摆脱这两个通知。

我没有发现任何明显的内存管理问题。您发布的所有代码似乎都在创建自动发布的对象，应该没问题。