Question

我在我的iPad应用程序中同步来自服务器的大约5000张图像。这些图像的大小约为2.5 GB，我的iPad也有足够的空间。

但在同步仅375张图片后，我的应用程序开始崩溃，原因如下

malloc: *** mmap(size=1048576) failed (error code=12)
*** error: can't allocate region
*** set a breakpoint in malloc_error_break to debug

2013-02-14 06:20:50.058 AAA[1250:907] ***

Terminating app due to uncaught exception 'NSMallocException',
 reason: 'Attempt to allocate 1048576 bytes for NS/CFData failed'

*** First throw call stack:

我正在使用核心数据在文档目录中保存图像。

如果对申请保存数据有任何限制，请指导我。我正在主线上执行所有这些操作。

 for (int i = 0; i < [shadowElement3 count]; i++)
        {
            NSMutableArray* array = [[NSMutableArray alloc] init];
            Product* failedBankInfo = [NSEntityDescription insertNewObjectForEntityForName:@"Product"                                                                    inManagedObjectContext:context];

            NSXMLElement* element11    = [shadowElement3 objectAtIndex:i];
            NSString* strPath = [element11 stringValueForNode:@"B1_COD"];

            NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask,YES);
            NSString *documentsDirectory = [paths objectAtIndex:0];
            NSString *savedImagePath = [documentsDirectory stringByAppendingPathComponent:strPath];

            NSLog(@"%@",[element11 stringValueForNode:@"img"]);
            NSData* receivedData = [NSData dataWithContentsOfURL:[NSURL URLWithString:              [element11 stringValueForNode:@"img"]]];
            [receivedData writeToFile:savedImagePath atomically:YES];

            [array addObject:savedImagePath];

}

Answer 1

您可能需要使用自动释放pool。根据该文档，“如果你编写一个创建许多临时对象的循环。”

Answer 2

有几件事：

您似乎每次都通过循环重新创建数组。
看起来你正在创建许多自动释放的对象。鉴于您可能正在创建几千个，您可能希望将它们包装在@autoreleasepool块中。
每次循环时都会重新创建几个变量，这些变量似乎是相同的。将它们拉出循环。
将上下文的撤消管理器设置为nil。这有助于减少内存开销。
最后，我不确定你是否在主线程上执行此操作，但如果数据连接速度较慢，dataWithContentsOfURL将阻塞主线程。您可能希望确保从主线程执行此操作。这是另一个问题的主题。
您可能希望使用enumerateObjectsUsingBlock:而不是for / loop。有关原因，请参阅here。

尝试以下内容：

NSMutableArray* array = [[NSMutableArray alloc] initWithCapacity:[shadowElement3 count]];
NSXMLElement* element11;
NSString* strPath;
NSString *savedImagePath;
Product* failedBankInfo;

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask,YES);
NSString *documentsDirectory = [paths objectAtIndex:0];

[context setUndoManager:nil];

for (int i = 0; i < [shadowElement3 count]; i++)
{

   @autoreleasepool{
      failedBankInfo = [NSEntityDescription insertNewObjectForEntityForName:@"Product"                                                                    inManagedObjectContext:context];
      element11 = [shadowElement3 objectAtIndex:i];
      strPath = [element11 stringValueForNode:@"B1_COD"];
      savedImagePath= [documentsDirectory stringByAppendingPathComponent:strPath];

      NSData* receivedData = [NSData dataWithContentsOfURL:[NSURL URLWithString:                       [element11 stringValueForNode:@"img"]]];
      [receivedData writeToFile:savedImagePath atomically:YES];
      [array addObject:savedImagePath];

      // you don't seem to be doing anything with the Managed Object you created,
      // I assume you are saving the path.  So do so and batch save the context.
      // This will help free up memory.
      failedBankInfo.pathName = savedImagePath;
      if ( i % 100 ==0 ){
          NSError *error;
          [context performBlock:^{

             [context save:&error];
             // handle error

             // reset the context cause you don't seem to be doing anything else
             // with the objects.  This will free up memory
             [context reset];
          }];
      }
  }

}

// One last save
NSError *error;
[context performBlock:^{
    [context save:&error];
    // handle error is exercise for the reader.

    // reset the context cause you don't seem to be doing anything else
    // with the objects.  This will free up memory
    [context reset];
}];

祝你好运。

保存250 MB数据后iPad应用程序崩溃

2 个答案: