为什么我不使用JSON使用Decodable？

Question

I try get json but it doesn't work for me. What i'm doing wrong? JSON My struct

struct Stock: Decodable {
  let category_name: String?
  let privileges: [StockInfo]?
}

struct StockInfo: Decodable {
  let id: String?
  let active_to: String?
  let title: String?
  let title_size: String?
  let preview_picture_path: String?
  let preview_picture_text: String?
  let picture_text_size: String?
  let marked: String?
  let preview_text: String?
  let code_block: [CodeBlockInfo]?    
}

struct CodeBlockInfo: Decodable {
  let button_title: String?
  let button_font_color: String?
  let button_back_color: String?
  let type: String?
  let code_text: String?
  let code_pict: String?
  let description: String?
}

Answer 1

1- CodeBlock is a dictionary not an array

let code_block:CodeBlockInfo

2- Decode like this

let res = try? JSONDecoder().decode([Stock].self,from:jsonData)

3- If you're sure that a key will always return remove the trailing ?