Question

我正在尝试从包含170,000多个字典的JSON文件中填充CoreData。 json的解析很快，但是当我开始尝试添加到CoreData时，我阻塞主线程很长一段时间，然后应用程序最终崩溃。它在调用方法时崩溃[UIDocument saveToUrl：forSaveOperation：completionHandler]这是我的代码。如果有人知道是什么导致它崩溃或者更有效的方式加载CoreData，那将非常感激。

@property (nonatomic, strong) UIManagedDocument *wordDatabase;

- (void)viewWillAppear:(BOOL)animated
  {
    [super viewWillAppear:animated];
    if (!self.wordDatabase) {
      NSURL *url = [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject];
      url = [url URLByAppendingPathComponent:@"Word Database"];
      self.wordDatabase = [[UIManagedDocument alloc] initWithFileURL:url];
    }
 }

- (void)setWordDatabase:(UIManagedDocument *)wordDatabase
  {
    if (_wordDatabase != wordDatabase) {
      _wordDatabase = wordDatabase;
      [self useDocument];
    }
  }

- (void)useDocument
  {
    if (![[NSFileManager defaultManager] fileExistsAtPath:[self.wordDatabase.fileURL path]]) {
      // does not exist on disk, so create it
      [self.wordDatabase saveToURL:self.wordDatabase.fileURL forSaveOperation:UIDocumentSaveForCreating completionHandler:^(BOOL success) {
          [self setupFetchedResultsController];
          [self prepopulateWordDatabaseWithDocument:self.wordDatabase];
       }];
     }
  }

- (void)prepopulateWordDatabaseWithDocument:(UIManagedDocument *)document
  {
    dispatch_queue_t fetchQ = dispatch_queue_create("Word Fetcher", NULL);
    dispatch_async(fetchQ, ^{
    //Fetch the words from the json file
    NSString *fileString = [[NSBundle mainBundle] pathForResource:@"words" ofType:@"json"];
    NSString *jsonString = [[NSString alloc] initWithContentsOfFile:fileString encoding:NSUTF8StringEncoding error: NULL];
    NSData *jsonData = [jsonString dataUsingEncoding:NSUTF8StringEncoding];
    NSError *error;
    NSArray *words = [NSJSONSerialization JSONObjectWithData:jsonData options:NSJSONReadingMutableContainers error:&error];
    [document.managedObjectContext performBlock:^{
        for (NSDictionary *dictionary in words)
        {
            [Word wordFromDictionary:dictionary inManagedObjectContext:document.managedObjectContext];
        }

        [document saveToURL:document.fileURL forSaveOperation:UIDocumentSaveForOverwriting completionHandler:NULL];
      }];
    });

   dispatch_release(fetchQ);
 }

Answer 1

我最终做的是阻止我的应用程序崩溃，分配了一个新的NSManagedObjectContext并在后台执行了我的所有加载。保存后，我调用了我的NSFetchedResultsController并重新填充了表。

- (void)prepopulateWordDatabaseWithDocument:(UIManagedDocument *)document
 {
     NSManagedObjectContext *backgroundContext = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSPrivateQueueConcurrencyType];
     backgroundContext.undoManager = nil;
     backgroundContext.persistentStoreCoordinator = document.managedObjectContext.persistentStoreCoordinator;
     [backgroundContext performBlock:^{
         NSString *fileString = [[NSBundle mainBundle] pathForResource:@"words" ofType:@"json"];
         NSString *jsonString = [[NSString alloc] initWithContentsOfFile:fileString encoding:NSUTF8StringEncoding error: NULL];
         NSData *jsonData = [jsonString dataUsingEncoding:NSUTF8StringEncoding];
         NSError *parseError;
         NSArray *words = [NSJSONSerialization JSONObjectWithData:jsonData options:NSJSONReadingMutableContainers error:&parseError];

         for (NSDictionary *dictionary in words)
         {
             [Word wordFromDictionary:dictionary inManagedObjectContext:backgroundContext];
         }

         NSError *loadError;
         if ([backgroundContext save:&loadError]) {
             dispatch_async(dispatch_get_main_queue(), ^{
                 [self setupFetchedResultsController];
             });
         }
     }];
 }

从大型JSON加载核心数据导致应用程序崩溃

1 个答案: