Ios 使用requestImageDataForAsset方法显示虚拟内存耗尽

当我使用requestImageDataForAsset：存储一些数据时，我的相机卷中有10000多张照片，并且我已经为requestImageDataForAsset添加了@autoreleasepool：但是当我再次运行requestImageDataForAsset方法时，应用程序

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撞车 并显示此错误：
错误：libBacktraceRecording.dylib:allocate\u free\u list\u pages（）--虚拟内存耗尽

for (PHAsset *asset in albumResult){ //there are over 10000 photos

                    if (asset.mediaType == PHAssetMediaTypeImage) {
                        __block NSString *orgFilename = nil;
                      @autoreleasepool {
                        [[PHImageManager defaultManager]
                         requestImageDataForAsset:asset
                         options:imageRequestOptions
                         resultHandler:^(NSData *imageData, NSString *dataUTI,
                                         UIImageOrientation orientation,
                                         NSDictionary *info)
                         {
                             if ([info objectForKey:@"PHImageFileURLKey"]) {
                                 NSString *photoURL = [[info objectForKey:@"PHImageFileURLKey"]absoluteString];
                                 orgFilename = [[photoURL componentsSeparatedByString:@"/"] lastObject];
                    NSArray *keys = [NSArray arrayWithObjects:@"type",@"title",@"status",@"res_resURL",@"path",@"shareName",@"authtok",@"nasIp",@"macAddr",@"albumName",nil];
                    NSArray *values = [NSArray arrayWithObjects:@"assetID",orgFilename,@"queue",asset.localIdentifier,destinationPath,shareName,authToken,nasIp,macAddr,albumName, nil];
                    NSDictionary *dict = [NSDictionary dictionaryWithObjects:values forKeys:keys];
                    [scanedData addObject:dict];
                             }
                         }];
                       }
        }

为什么@autoreleasepool不释放内存？ 我在xCode debug navigator中检查了使用过的内存，它总是显示130MB左右，似乎自动释放池不起作用