iphone - 使用 SDURLCache(NSURLCache 的子类)时的内存泄漏

Question

我正在使用 Olivier Poitrey's SDURLCache (github 链接)作为 NSURLCache 的替代方案，以在 iPhone 应用程序中启用磁盘缓存。

它工作得很好，但奇怪的是，当返回磁盘缓存对象时会泄漏 NSHTTPURLResponseInternal(当从内存返回对象或未找到对象时没有泄漏)。以下代码片段显示了 SDURLCache 如何从磁盘读取数据:

- (NSCachedURLResponse *)cachedResponseForRequest:(NSURLRequest *)request
{
    NSCachedURLResponse *memoryResponse = [super cachedResponseForRequest:request];
    if (memoryResponse)
    {
        return memoryResponse;
    }

    NSString *cacheKey = [SDURLCache cacheKeyForURL:request.URL];

    // NOTE: We don't handle expiration here as even staled cache data is necessary for NSURLConnection to handle cache revalidation.
    //       Staled cache data is also needed for cachePolicies which force the use of the cache.
    NSMutableDictionary *accesses = [self.diskCacheInfo objectForKey:kSDURLCacheInfoAccessesKey];
    if ([accesses objectForKey:cacheKey]) // OPTI: Check for cache-hit in a in-memory dictionnary before to hit the FS
    {
        NSCachedURLResponse *diskResponse = [NSKeyedUnarchiver unarchiveObjectWithFile:[diskCachePath stringByAppendingPathComponent:cacheKey]];
        if (diskResponse)
        {
            // OPTI: Log the entry last access time for LRU cache eviction algorithm but don't save the dictionary
            //       on disk now in order to save IO and time
            [accesses setObject:[NSDate date] forKey:cacheKey];
            diskCacheInfoDirty = YES;

            // OPTI: Store the response to memory cache for potential future requests
            [super storeCachedResponse:diskResponse forRequest:request];
            return diskResponse;
        }
    }

    return nil;
}

每个 NSHTTPURLResponseInternal 泄漏的堆栈跟踪都包含对 SDURLCache 代码的两个引用。

第一个指向行 [accesses setObject:[NSDate date] forKey:cacheKey];。第二个也是最新的指向以下内容:

@implementation NSCachedURLResponse(NSCoder)

- (id)initWithCoder:(NSCoder *)coder
{
    return [self initWithResponse:[coder decodeObjectForKey:@"response"]
                             data:[coder decodeDataObject]
                         userInfo:[coder decodeObjectForKey:@"userInfo"]
                    storagePolicy:[coder decodeIntForKey:@"storagePolicy"]];
}

@end 

有没有人遇到过这个问题？关于解决方案的任何想法？让我知道是否应该发布更多代码示例。

干杯。

更新:Tweet from Olivier Poitrey ，代码作者

I'm planning on removing the NSURLCache inherency and handle the memory cache, it may fix the leak

Answer 1

本身不是答案，而是意识。 iOS 5.0 及更高版本上的 NSURLCache 现在默认缓存到闪存和 RAM。因此，如果您使用 SDURLCache 以获得磁盘缓存，并且目标是 5.0 及更高版本，则没有理由使用 SDURLCache。