苹果的可达内存泄漏

Question

我在我的非弧形项目中使用苹果的Reachabiliry课程。当我用仪器运行它来查找内存泄漏时，它引用了Reachability方法。以下是问题所在：

+ (instancetype)reachabilityWithAddress:(const struct sockaddr_in *)hostAddress;
{
    SCNetworkReachabilityRef reachability = SCNetworkReachabilityCreateWithAddress(kCFAllocatorDefault, (const struct sockaddr *)hostAddress);

    WReachability* returnValue = NULL;

    if (reachability != NULL)
    {
        returnValue = [[self alloc] init];
        if (returnValue != NULL)
        {
            returnValue->reachabilityRef = reachability;
            returnValue->localWiFiRef = NO;
        }
    }
    return returnValue;
}

泄漏的对象是可达性和returnValue。我知道SCNetworkReachabilityCreateWithAddress创建了一个新实例，我必须使用CFRelease，但是它发生在dealloc中！

- (void)dealloc
{
    [self stopNotifier];
    if (reachabilityRef != NULL)
    {
        CFRelease(reachabilityRef);
    }
    [super dealloc];
}

那么，我能做些什么来避免内存泄漏呢？

UPD:也许问题在于如何调用可达性？我使用这种方法：

+ (instancetype)reachabilityForInternetConnection;
{
    struct sockaddr_in zeroAddress;
    bzero(&zeroAddress, sizeof(zeroAddress));
    zeroAddress.sin_len = sizeof(zeroAddress);
    zeroAddress.sin_family = AF_INET;

    return [self reachabilityWithAddress:&zeroAddress];
}

然后我就这样叫Reachability：

[[Reachability reachabilityForInternetConnection] startNotifier];

不要将它分配给任何对象，只需使用这一行。我试图将这个调用更改为：

Reachability *reachability = [[Reachability reachabilityForInternetConnection] autorelease];
[reachability startNotifier];

但是在这个分析器告诉我“太多的自动释放”之后。

Answer 1

如果returnValue等于空可达对象泄漏，则在本例中您应该释放它。此外，根据Cocoa命名约定(ref/doc/uid/20000994-SW1)，您必须返回自动释放的对象：

+ (instancetype)reachabilityWithAddress:
{
    ...
     returnValue = [[[self alloc] init] autorelease];

或者重命名要启动的方法，例如，如果您不想返回一个自动释放的对象，可以从new：newReachabilityWithAddress或类似的东西开始。

尝试在Xcode中运行静态分析器，可以帮助发现问题。

Answer 2

@Alexart的答案对我有效，但是如果您想要一个简化的版本，请使用

+(instancetype)reachabilityWithAddress:(void *)hostAddress
{
   SCNetworkReachabilityRef ref = SCNetworkReachabilityCreateWithAddress(kCFAllocatorDefault, (const struct sockaddr*)hostAddress);
   if (ref)
   {
      id reachability = [[self alloc] initWithReachabilityRef:CFBridgingRetain((__bridge id)ref)];
      CFRelease(ref);
      return reachability;
   }
   return nil;

}

Answer 3

我认为更好的做法是：

+ (Reachability*) reachabilityWithHostName: (NSString*) hostName;
{
    Reachability* retVal = NULL;
    SCNetworkReachabilityRef reachability = SCNetworkReachabilityCreateWithName(NULL, [hostName UTF8String]);
    if(reachability!= NULL)
    {
        retVal= [[self alloc] init];
        if(retVal!= NULL)
        {
            retVal->reachabilityRef = reachability;
            retVal->localWiFiRef = NO;
        }
        else
        {
            CFRelease(reachability);
        }
    }
    return retVal;
}