NSMetadataQueryDidUpdateNotification叫來幾個時間

Question

我啓用的iCloud UIDocument在我的應用程序，我存儲在雲上的文檔，該文檔打包，對收到的iCloud文檔的更新的通知我這樣做：

- (void)startQuery { 

    [self stopQuery]; 

    NSLog(@"Starting to watch iCloud dir..."); 

    _query = [self documentQuery]; 

    [[NSNotificationCenter defaultCenter] addObserver:self 
              selector:@selector(processiCloudFiles:) 
               name:NSMetadataQueryDidFinishGatheringNotification 
               object:nil]; 
    [[NSNotificationCenter defaultCenter] addObserver:self 
              selector:@selector(processiCloudFiles:) 
               name:NSMetadataQueryDidUpdateNotification 
               object:nil]; 

    [_query startQuery]; 
} 

- (void)stopQuery { 

    if (_query) { 

     NSLog(@"No longer watching iCloud dir..."); 

     [[NSNotificationCenter defaultCenter] removeObserver:self name:NSMetadataQueryDidFinishGatheringNotification object:nil]; 
     [[NSNotificationCenter defaultCenter] removeObserver:self name:NSMetadataQueryDidUpdateNotification object:nil]; 
     [_query stopQuery]; 
     _query = nil; 
    } 

} 

- (NSMetadataQuery *)documentQuery { 

    NSMetadataQuery * query = [[NSMetadataQuery alloc] init]; 
    if (query) { 

     [query setSearchScopes:[NSArray arrayWithObject: 
           NSMetadataQueryUbiquitousDocumentsScope]]; 

     NSPredicate *pred = [NSPredicate predicateWithFormat:@"%K == %@", 
          NSMetadataItemFSNameKey, 
          kFILENAME]; 
     [query setPredicate:pred]; 

    } 
    return query; 

} 

- (void)processiCloudFiles:(NSNotification *)notification { 

    [_query disableUpdates]; 

    if ([_query resultCount] == 1) { 
     NSMetadataItem *item = [_query resultAtIndex:0]; 
     NSURL *url = [item valueForAttribute:NSMetadataItemURLKey]; 

     if (!self.folder) { 
      self.folder = [[MyDocument alloc] initWithFileURL:url]; 
     } 
     [self.folder openWithCompletionHandler:^ (BOOL success) { 
      if (success) { 
       NSLog(@"loadData - doc opened from cloud %i", self.folder.count); 
       [self.folder closeWithCompletionHandler:^(BOOL success) { 
        NSLog(@"doc closed"); 
       } 
       ]; 
      } else { 
       NSLog(@"failed to open"); 
      } }]; 

    } 
} 

啓動所有我打電話[self startQeury]，問題是NSMetadataQueryDidUpdateNotification稱爲通知幾個時間，如果我做的文檔中的變化，你可以怎麼看日誌：

2013-10-12 01:43:54.933 Starting to watch iCloud dir... 
2013-10-12 01:43:56.119 loadData - doc opened from cloud 56 
2013-10-12 01:43:56.120 doc closed 
2013-10-12 01:44:01.552 item deleted 

，你可以在這裏看到我做交流在這裏下面你可以看到產卵4通知：

2013-10-12 01:44:08.110 loadData - doc opened from cloud 55 
2013-10-12 01:44:08.111 doc closed 
2013-10-12 01:44:11.942 loadData - doc opened from cloud 55 
2013-10-12 01:44:11.943 doc closed 
2013-10-12 01:44:13.198 loadData - doc opened from cloud 55 
2013-10-12 01:44:13.199 doc closed 
2013-10-12 01:44:14.925 loadData - doc opened from cloud 55 
2013-10-12 01:44:14.926 doc closed 

爲什麼叫幾次？在我的應用程序中，當更新完成時我需要處理更改，所以我只需要一個通知...我該怎麼辦？

編輯： 我有什麼嘗試@rmaddy在回答提示，我有嘗試這個辦法：

if ([[item valueForAttribute:NSMetadataUbiquitousItemIsDownloadedKey] boolValue]) { 

     if (!self.folder) { 
      self.tvfilesFolder = [[MyDocument alloc] initWithFileURL:url]; 
     } 
     [self.folder openWithCompletionHandler:^ (BOOL success) { 
      if (success) { 
       NSLog(@"loadData - doc opened from cloud %i", self.folder.count); 
       [self.folder closeWithCompletionHandler:^(BOOL success) { 
        NSLog(@"doc closed"); 
       } 
       ]; 
      } else { 
       NSLog(@"failed to open"); 
      } }]; 
    } 

但同樣我的問題是這樣的日誌：

2013-10-12 10:35:26.084 Starting to watch iCloud dir... 
2013-10-12 10:35:30.306 loadData - doc opened from cloud 54 
2013-10-12 10:35:30.307 doc closed 

那麼我編輯了一個文件，這是日誌：

2013-10-12 10:35:53.233 loadData - doc opened from cloud 54 
2013-10-12 10:35:53.235 doc closed 
2013-10-12 10:35:56.703 loadData - doc opened from cloud 54 
2013-10-12 10:35:56.704 doc closed 
2013-10-12 10:35:58.489 loadData - doc opened from cloud 54 
2013-10-12 10:35:58.490 doc closed 

我該怎麼辦？

編輯2：

我已經嘗試用這樣的：

if ([[item valueForAttribute:NSMetadataUbiquitousItemIsDownloadedKey] boolValue] && [[item valueForAttribute:NSMetadataUbiquitousItemIsUploadedKey] boolValue]) { 
.... 
} 

，似乎工作，你在想什麼？我可以處理所有的時間有變化，或者我可以以這種方式錯過一些通知？

Answer 1

該通知因許多原因而被調用。當文件首次上傳到iCloud並從iCloud下載文件時。您還會獲得有關上傳和下載百分比的更新。如果查看文件的各種屬性，可以看到所有這些。

我用一個小的調試方法記錄每個元數據項：

- (void)echoMetadataItem:(NSMetadataItem *)item { 
    NSString *path = [item valueForAttribute:NSMetadataItemPathKey]; 
    NSString *display = [item valueForAttribute:NSMetadataItemDisplayNameKey]; 
    NSURL *url = [item valueForAttribute:NSMetadataItemURLKey]; 
    NSString *name = [item valueForAttribute:NSMetadataItemFSNameKey]; 
    NSNumber *downloaded = [item valueForAttribute:NSMetadataUbiquitousItemIsDownloadedKey]; 
    NSNumber *downloading = [item valueForAttribute:NSMetadataUbiquitousItemIsDownloadingKey]; 
    NSNumber *uploaded = [item valueForAttribute:NSMetadataUbiquitousItemIsUploadedKey]; 
    NSNumber *uploading = [item valueForAttribute:NSMetadataUbiquitousItemIsUploadingKey]; 
    NSDate *createData = [item valueForAttribute:NSMetadataItemFSCreationDateKey]; 
    NSDate *updateDate = [item valueForAttribute:NSMetadataItemFSContentChangeDateKey]; 
    NSNumber *hasConflicts = [item valueForAttribute:NSMetadataUbiquitousItemHasUnresolvedConflictsKey]; 

    RMLogInfo(@"Metadata item name: %@, display: %@, path: %@, url: %@, ded: %@, ding: %@, ued:%@, uing: %@, created: %@, updated: %@, conflicts: %@", name, display, path, url, downloaded, downloading, uploaded, uploading, createData, updateDate, hasConflicts); 
} 

也有鑰匙拿到上傳和下載的百分比。

如果您想要處理通知一次，您可以檢查文件是否已下載。