Question

我正在检索一些JSON并将其存储在一个数组中。然后在一个调度块中，我遍历数组并调用一个单独的方法将每个数组项插入到Core Data中。像这样：

dispatch_async(dispatch_get_main_queue(), { [unowned self] in
    for result in jsonCategoriesArray {
      if let category = NSEntityDescription.insertNewObjectForEntityForName("Category", inManagedObjectContext: CoreDataStack.sharedInstance.managedObjectContext) as? Category {
        self.insertCategory(category, usingJSON: result)
      }
    }

    self.saveCoreDataContext()
    self.loadSavedCategories()
})

这是插入方法：

private func insertCategory(category: Category, usingJSON json: JSON) {
  let formatter = NSNumberFormatter()
  formatter.generatesDecimalNumbers = true

  category.id = (formatter.numberFromString(json["ID"].stringValue) as? NSDecimalNumber)!
  category.categoryID = (formatter.numberFromString(json["IDKategori"].stringValue) as? NSDecimalNumber)!
  category.title = json["KategoriBaslik"].stringValue
  category.subCategoryCount = (formatter.numberFromString(json["AltKategoriSayi"].stringValue) as? NSDecimalNumber)!

  guard let url = NSURL(string: json["KategoriResim"].stringValue) else {
    return
  }

  NSURLSession.sharedSession().dataTaskWithURL(url) { (data, response, error) in
    guard let httpUrlResponse = response as? NSHTTPURLResponse where httpUrlResponse.statusCode == 200,
        let mimeType = response?.MIMEType where mimeType.hasPrefix("image"),
        let data = data where error == nil
    else {
      print("Problem downloading the image of the category with id: \(category.id) and name: \(category.title)")
      return
  }

    dispatch_async(dispatch_get_main_queue()) { [unowned self] in
      category.logo = data
      self.saveCoreDataContext()
      NSNotificationCenter.defaultCenter().postNotificationName("CategoryUpdate", object: nil)
    }
  }.resume()
}

唯一的问题是使用NSURLSession的图像下载会多次导致以下错误：

2016-07-07 12:33:21.284 En Yakın[24040:1541295] CoreData: error: Mutating a managed object 0x790995a0 <x-coredata:///Category/t045D239A-9032-4B07-B870-46AA156B1D9B15> (0x79099560) after it has been removed from its context.

图像是大约8 KB的缩略图，存储为Binary Data。我该怎么办呢？

在Core Data中存储下载的图像会导致错误

0 个答案: