CloudKit查询时间 [英] CloudKit Query Time

问题描述

我刚刚开始试用CloudKit，查询时间有些慢。这是我正在使用的一些示例代码：

I've just started trialling CloudKit and am having some pretty slow query times. Here is some sample code I am using:

//CLOUDKIT
    CKContainer *container = [CKContainer defaultContainer];
    CKDatabase *privateDatabase = [container privateCloudDatabase];

    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"TRUEPREDICATE"];
    CKQuery *query = [[CKQuery alloc] initWithRecordType:@"FlightLog" predicate:predicate];

    [privateDatabase performQuery:query inZoneWithID:nil completionHandler:^(NSArray *results, NSError *error) {
        //SUCCESS
        if (!error)
        {
            UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"SUCCESS" message:@"IT WORKED" delegate:self cancelButtonTitle:@"dismiss" otherButtonTitles:nil];
            [alert show];

            NSLog(@"%@", @"fetchFlights success!");
            NSLog(@"%@", self.fetchedRecords);

            self.fetchedRecords = results;
            [self.tableView reloadData];
        }
        //ERROR
        else
        {
            UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"error" message:error.localizedDescription delegate:self cancelButtonTitle:@"dismiss" otherButtonTitles:nil];
            [alert show];

            NSLog(@"%@", error);
        }

    }];

我得到了私有数据库，并查询了所有记录。在仪表板中仅添加了四个简单的代码。

I get the private database, and query for all records. There is just four simple ones I added in the dashboard.

调用此代码后，我可以从控制台日志中看到成功消息几乎立即被调用，并带有一个结果数组为空。然后，稍后返回结果，如日志中所示。但是，没有显示警报视图，并且结果在我的表格中显示了大约3-4秒。

Upon calling this code, I can see from my console log that the success message gets called almost immediately, with a null results array. Then moments later, the results are returned, as seen in the log. However, the alert view isn't shown and results displayed in my table for about 3-4 more seconds.

发生了什么事！！

谢谢。

推荐答案

已解决。正如Edwin提到的，我不知道回调是在后台线程上进行的。因此，当我在完成块中调用 [self.tableView reloadData] 时，它也在后台线程上运行。

This is resolved. As Edwin mentions, I didn't know that the callback is on a background thread. So when I call [self.tableView reloadData] in the completion block, it is also running on the background thread.

将其返回主线程后，表视图将在大约一秒钟内重新加载。如果在与回调相同的线程上运行，则耗时约4-5秒。

By putting it back on the main thread, the table view reloads within about a second. Vs taking about 4-5 seconds if running on the same thread as the callback.

    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), ^{
        dispatch_async(dispatch_get_main_queue(), ^{
                           [self.tableView reloadData];
                       });
    });

让我知道我是否被误解了，但我认为这就是发生的事情。

Let me know if I have misunderstood, but I think that's what has happened.

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