ios - NSOperationQueue currentQueue 不工作

Question

我正在尝试在 currentQueue 上运行 AFURLConnectionOperation，因为我想让我的主线程空闲以供用户交互，但是当我调用 mainQeue 时没有任何反应。

但是，如果我在 mainQueue 上调用相同的 AFURLConnectionOperation，它会完美运行。

请看下面的代码

// Send Batch
        NSArray *operations = [AFURLConnectionOperation batchOfRequestOperations:mutableOperations progressBlock:^(NSUInteger numberOfFinishedOperations, NSUInteger totalNumberOfOperations) {
            NSLog(@"%lu of %lu complete", (unsigned long)numberOfFinishedOperations, (unsigned long)totalNumberOfOperations);
        } completionBlock:^(NSArray *operations) {
            // check batch response
            NSError *error;
            for (AFHTTPRequestOperation *op in operations) {
                if (op.isCancelled){
                    return ;
                }
                if (op.responseObject){
                    // Current JSON Batch complete
                    NSMutableArray *jsonObject = [NSJSONSerialization JSONObjectWithData:op.request.HTTPBody options:kNilOptions error:&error];
                    // Update sent_flag using current chunk
                    [[SyncModel sharedInstance] updateSentFlag:jsonObject];
                }
                if (op.error){
                    error = op.error;
                    NSLog(@"Error == %@", error);
                }
            }
        }];

然后最后我调用以下代码之一

[[NSOperationQueue mainQueue] addOperations:operations waitUntilFinished:NO]; // this works
[[NSOperationQueue currentQueue] addOperations:operations waitUntilFinished:NO]; // this dose not work

Answer 1

原因是

You can use this method from within a running operation object to get a reference to the operation queue that started it. Calling this method from outside the context of a running operation typically results in nil being returned.

所以，我想，如果你记录 [NSOperationQueue currentQueue]，它是 nil

如果你想要一个新队列，使用

[[NSOperationQueue alloc] init];