CODEWITHSUNDEEP
jsonswiftdocument
Part_Time_Nerd
Part_Time_Nerd

Reputation: 1014

Why am I am getting an "Invalid (non-string) key in JSON dictionary" error message?

I am trying to use Swift to create a reference to an image and storing it in documents using a dictionary and JSON. I believe that I created the correct syntax for dictionary based on another SO answer that I found. The error message below happens when I press the button with function addButtonClicked. What am i doing wrong?

Error message:

Invalid (non-string) key in JSON dictionary

// Inside UICollectionViewCell 
var representedAssetIdentifier: String? = nil

// Inside  UIViewController
  var count: Int = 0
  var dictionary: [Int:String] = [:]

  @objc func addButtonClicked() {        
      do {
          let fileURL = try FileManager.default
              .url(for: .applicationSupportDirectory, in: .userDomainMask, appropriateFor: nil, create: true)
              .appendingPathComponent("example.json")
          
          try JSONSerialization.data(withJSONObject: dictionary).write(to: fileURL)
      } catch {
          print("Error report: \(error.localizedDescription)")
      }
      let newViewController = PickerTest3()
      self.navigationController?.pushViewController(newViewController, animated: true)
  }

  func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
      if let cell = collectionView.cellForItem(at: indexPath) as? ImageCell {
          let newCount = count
          dictionary.updateValue(cell.representedAssetIdentifier!, forKey: newCount)
          count += 1
          selectedCells.append(indexPath)
          cell.index = selectedCells.count
      }
  }

Upvotes: 1

Views: 1422

Answers (1)

Leo Dabus
Leo Dabus

Reputation: 236260

The error message is pretty clear. You can not create a JSON string using a dictionary that has integer keys. You need to use strings.

Note: Not related to your question but you should not write any file directly to the application support directory:

Use this directory to store all app data files except those associated with the user’s documents. For example, you might use this directory to store app-created data files, configuration files, templates, or other fixed or modifiable resources that are managed by the app. An app might use this directory to store a modifiable copy of resources contained initially in the app’s bundle. A game might use this directory to store new levels purchased by the user and downloaded from a server. All content in this directory should be placed in a custom subdirectory whose name is that of your app’s bundle identifier or your company. In iOS, the contents of this directory are backed up by iTunes and iCloud.

File System Basics

Upvotes: 2

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