ios - 在 NSOperationQueue 和 mainQueue 之间传递数据

Question

我环顾四周想得到一个确切的答案，但没找到。

简而言之:将数据从操作队列传递到主队列的最佳方式是什么？

我有一个繁重的计算任务在操作队列中运行以计算数组。我想将结果传回主队列并在那里将它们用作 UITableView 的基础。

问题是，考虑到内存管理，我不确定传递此数据的最佳方式是什么。 (该项目不使用 ARC)。像这样在 operationQueueArray 上使用 autorelease 是否安全:

[operationQueue addOperationWithBlock:^{
    NSMutableArray *operationQueueArray = [[[NSMutableArray alloc] init] autorelease];

    // do some heavy compute and fill the results into the operationQueueArray

    [[NSOperationQueue mainQueue] addOperationWithBlock:^{
        // passing the data
        [mainQueueArray removeAllObjects];
        [mainQueueArray addObjectsFromArray:operationQueueArray];

        [myTableView reloadData];
    }];
}];

用这段代码保证operationQueueArray在mainQueue中不被释放吗？

或者我应该在某处放置一些手动版本？有没有更好的方法甚至指南如何做到这一点？

Answer 1

  [operationQueue addOperationWithBlock:^{
     NSMutableArray *operationQueueArray = [[[NSMutableArray alloc] init] autorelease];
     // do some heavy compute and fill the results into the operationQueueArray
     // If you log current thread here it should be a worker thread
     // do a sync call to your main thread with the computed data. Your async thread will not release its context, data, etc untill you finsihed passsing your data,
     // in other words, untill the dispatch_sync block does not finish
     dispatch_queue_t mainQueue = dispatch_get_main_queue();
     dispatch_sync(mainQueue, ^{
        // passing the data
        // If you do a log for [NSThread currentThread] here, it should be your main thread (UI thread)
        // It's safe to pass data to your table view as log as you retain your objects in your Table view controller data source array once you pass them there
        // and release them when your controller is released
        [mainQueueArray removeAllObjects];
        [mainQueueArray addObjectsFromArray:operationQueueArray];
        // Adding your objects to your main queue array will do +1 retain count to your objects.
        // They will only get released when your array is released.
        [myTableView reloadData];
     });
  }];