Apple的可达性内存泄漏

Question

我在非弧项目中使用了苹果的Reachabiliry课程.当我使用仪器运行以查找内存泄漏时,它会引用Reachability方法.这是问题所在:

+ (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CFRelease它,但它发生在dealloc!

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

那么我该怎么做才能避免内存泄漏呢？

UPD:可能问题在于如何调用可达性？我用这个方法:

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

    return [self reachabilityWithAddress:&zeroAddress];
}

然后我打电话给Reachability:

[[Reachability reachabilityForInternetConnection] startNotifier];

并且不要将它分配给任何对象,只需使用此行.我试图将此调用更改为:

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

但在此分析仪告诉我"太多自动释放"之后.

Answer 1

@Alexart的答案对我有用,但如果你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 2

我认为下一步做得更好:

+ (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;
}

Answer 3

如果 returnValue 等于 NULL 可达性对象泄漏，在这种情况下您应该释放它。另外，根据Cocoa命名约定（https://developer.apple.com/library/ios/documentation/cocoa/conceptual/MemoryMgmt/Articles/mmRules.html#//apple_ref/doc/uid/20000994-SW1），您必须返回autoreleased目的：

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

newReachabilityWithAddress或者，如果您不想返回自动释放的对象，则将方法重命名为从 new: 开始，或者类似的名称。

尝试在Xcode中运行静态分析器，它可以帮助发现问题。