苹果的可达性内存泄漏

Question

我在我的非弧项目中使用苹果的 Reachabilry 类。当我用仪器运行它来查找内存泄漏时，它指的是可达性方法。问题来了：

+ (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;
}

泄露的对象是可达性和returnValue。 我知道 SCNetworkReachabilityCreateWithAddress 创建了一个新实例，我必须 CFRelease 它，但它发生在 dealloc 中！

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

那么我该怎么做才能避免这里的内存泄漏？

更新： 也许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];
}

然后我这样调用可达性：

[[Reachability reachabilityForInternetConnection] startNotifier];

并且不要将它分配给任何对象，只需使用这一行。 我试图将此调用更改为：

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

但是在这个分析器告诉我“autorelease 太多”之后。

Answer 1

@Alexart 回答对我有用，但如果您想要简化版本，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

我认为下一个方法更好：

+ (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 可达性对象被泄露，你应该在这种情况下释放它。同样根据 Cocoa 命名约定 (https://developer.apple.com/library/ios/documentation/cocoa/conceptual/MemoryMgmt/Articles/mmRules.html#//apple_ref/doc/uid/20000994-SW1)，您必须返回自动释放的对象：

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

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

尝试在 Xcode 中运行静态分析器，它可以帮助发现问题。

Answer 4

启用 ARC 的解决方案Reachability 类。

1. 在问题行下方添加CFAutorelease(ref)。
2. 从dealloc 中删除CFRelease(self.reachabilityRef) 代码

更新dealloc

- (void)dealloc {
    [self stopNotifier];

    self.reachableBlock          = nil;
    self.unreachableBlock        = nil;
    self.reachabilityBlock       = nil;
    self.reachabilitySerialQueue = nil;
}

更新reachabilityWithAddress

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

    return nil;
}

更新reachabilityWithHostname

+ (instancetype)reachabilityWithHostname:(NSString*)hostname {
    SCNetworkReachabilityRef ref = SCNetworkReachabilityCreateWithName(NULL, [hostname UTF8String]);
    if (ref) {
        id reachability = [[self alloc] initWithReachabilityRef:ref];
        CFAutorelease(ref);
        return reachability;
    }

    return nil;
}

Answer 5

最新的reachability.m 似乎需要ARC，我的应用没有使用它。

我刚刚打开它：

1. 转到目标\构建阶段\编译源代码

2. 找到可达性并双击它

3. 添加-fobjc-arc

内存泄漏现在消失了

Answer 6

在dealloc中除了CFRelease外，对代码的正确修复如下。

看看下面的代码主体。类似的主体也需要进入reachabilityWithHostName 代码。

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

    Reachability* returnValue = NULL;

    if (reachability != NULL)
    {
        returnValue = [[self alloc] init];
        if (returnValue != NULL)
        {
            returnValue->_reachabilityRef = CFRetain(reachability);
            returnValue->_alwaysReturnLocalWiFiStatus = NO;
        }
         CFRelease(reachability);
    }
    return returnValue;
}