objective-c - 非 GC 应用程序中的内存管理 OS X __block 变量分配

Question

我有一个非 gc OS X 应用程序。在此应用程序中，我尝试从 block 内将对象分配给 block 变量。然后，另一个线程会从其所在的数组中清除该对象。我假设因为它是一个 non-gc 应用程序，所以 block_byref 结构正在设置 BLOCK_NEEDS_FREE 标志，并且 dispose 辅助函数正在清理向上的对象。副本是否足够安全？

- (void)assignFromArray
{
  __block NSObject iWantToKeep = nil;

  [myArray enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop)
  {
    if([[obj stringVar] isEqualToString:MyStringConst])
    {
       iWantToKeep = [obj copy];
       *stop = YES;
    }
  }];

/* Assume here that the array has been cleaned up by another thread
 * and all the objects in it have been released.
 *
 * Was a copy safe enough to survive the block_byref dispose
 * and the array objects being dealloc'd so that it can be accessed here?
 */
   NSLog(@"%@", [iWantToKeep stringVar]);

  //I only need it briefly, so it can be cleaned up here
  [iWantToKeep autorelease];
}

Answer 1

是的，效果很好。您只需确保在丢弃数组之前进行复制即可。