Generic function to parse local JSON from either a dictionary or array structure. Bundle. JSON. Parsing.

GenericJSONParsing.swift

extension Bundle {
  enum BundleError: Error {
    case noResource(String)
    case noContents(String)
    case decodingError(Error)
  }
  
  func parseJSONData<T: Decodable>(_ name: String, ext: String = "json") throws -> T {
    guard let path = Bundle.main.path(forResource: name, ofType: ext) else {
      throw BundleError.noResource(name)
    }
    guard let data = FileManager.default.contents(atPath: path) else {
      throw BundleError.noContents(path)
    }
    var elements: T
    do {
      elements = try JSONDecoder().decode(T.self, from: data)
    } catch {
      throw BundleError.decodingError(error)
    }
    return elements
  }
}

// Usage 

// dictionary 
do {
  let wrapper: ContactsWrapper = try Bundle.main.parseJSONData("contacts")
  dump(wrapper)
} catch {
  dump(error)
}


// array
do {
  let wrapper: [Weather] = try Bundle.main.parseJSONData("weather")
  dump(wrapper)
} catch {
  dump(error)
}