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我正在使用NSMetadataQuery来检查 iCloud 中的文件。在NSMetadataQueryDidFinishGatheringNotification处理程序内部，如果项目未下载或未下载，我开始使用下载它startDownloadingUbiquitousItemAtURL:fileURL:- 但最近，在两台设备上使用该应用程序后，文件似乎卡住了；startDownloadingUbiquitousItemAtURL:fileURL:不再开始下载。

这是代码的缩写形式：

    for (NSMetadataItem * result in query.results)
    {   
        NSURL *fileURL = [result valueForAttribute:NSMetadataItemURLKey];

        // snipped: checks that the item isn't hidden or already downloaded

        if (![fileURL getResourceValue:&isDownloading forKey:NSURLUbiquitousItemIsDownloadingKey error:&error] || !isDownloading)
        {
            NSLog(@"Error %@ getting downloading state for item at %@", error, fileURL);
            continue;
        }

        if ([isDownloading boolValue])
        {
            if (![fileURL getResourceValue:&downloadPercent forKey:NSURLUbiquitousItemPercentDownloadedKey error:&error] || !downloadPercent)
            {
                NSLog(@"Error %@ getting downloaded progress for item at %@", error, fileURL);
                continue;
            }

            NSLog(@"Item at %@ has is %@%% downloaded", fileURL, downloadPercent);
        }
        else
        {
            NSLog(@"Starting to download item at %@", fileURL);

            if ([[NSFileManager defaultManager] startDownloadingUbiquitousItemAtURL:fileURL error:&error])
            {
                isDownloading = nil;

                if ([fileURL getResourceValue:&isDownloading forKey:NSURLUbiquitousItemIsDownloadingKey error:&error] && isDownloading)
                {
                    if ([isDownloading boolValue])
                    {
                        NSLog(@"After starting to download, item at %@ is downloading.", fileURL);
                    }
                    else
                    {
                        NSLog(@"After starting to download, item at %@ is still not downloading!", fileURL);
                    }
                }
                else
                {
                    NSLog(@"Error %@ getting downloading state again for item at %@", error, fileURL);
                }
            }
            else
            {
                NSLog(@"Error %@ starting to download item at %@", error, fileURL);
            }
        }
    }

我看到的是：

Starting to download item at XXXXXXXX
After starting to download, item at XXXXXXXX is still not downloading!
Starting to download item at YYYYYYYY
After starting to download, item at YYYYYYYY is still not downloading!
Starting to download item at ZZZZZZZZ
After starting to download, item at ZZZZZZZZ is still not downloading!

为什么 startDownloadingUbiquitousItemAtURL:fileURL: 不开始下载项目？如果是由于某些冲突，我如何检测到该冲突？

更新：我查看了设备控制台，我看到了这个：

MyApp[NNNN] <Warning>: Starting to download item at XXXXXXXX
librariand[MMMM] <Error>: unable to download XXXXXXXX (0x8000000000000000)
MyApp[NNNN] <Warning>After starting to download, item at XXXXXXXX is still not downloading!
MyApp[NNNN] <Warning>Starting to download item at YYYYYYYY
librariand[MMMM] <Error>: unable to download YYYYYYYY (0x8000000000000000)
MyApp[NNNN] <Warning>After starting to download, item at YYYYYYYY is still not downloading!
MyApp[NNNN] <Warning>Starting to download item at ZZZZZZZZ
librariand[MMMM] <Error>: unable to download ZZZZZZZZ (0x8000000000000000)
MyApp[NNNN] <Warning>After starting to download, item at ZZZZZZZZ is still not downloading!

所以看起来至少守护进程被告知下载文件，即使它不能。有没有关于图书馆员错误的文档？

4

1 回答 1

2

Take a closer look at NSMetadataItem in your NSMetadataQuery results. When you iterating through the results of your query request you can get values for the following attributes instead: 

NSString * const NSMetadataUbiquitousItemIsDownloadedKey;
NSString * const NSMetadataUbiquitousItemIsDownloadingKey;
NSString * const NSMetadataUbiquitousItemIsUploadedKey;
NSString * const NSMetadataUbiquitousItemIsUploadingKey;
NSString * const NSMetadataUbiquitousItemPercentDownloadedKey;
NSString * const NSMetadataUbiquitousItemPercentUploadedKey;
于 2012-07-18T20:01:23.167 回答