The compiler cannot synthesise the required init(from:) method due to the weak reference, so you need to write it yourself. class Bookmark: Codable { weak var publication: Publication? var indexPath: [Int] var locationInText = 0 private enum CodingKeys: String, CodingKey { case indexPath case locationInText } init(publication: Publication?, indexPath: [Int]) { self.publication = publication self.indexPath … Read more
Another approach is to create an intermediate model that closely matches the JSON (with the help of a tool like quicktype.io), let Swift generate the methods to decode it, and then pick off the pieces that you want in your final data model: // snake_case to match the JSON and hence no need to write … Read more
Manually customising coding keys In your example, you’re getting an auto-generated conformance to Codable as all your properties also conform to Codable. This conformance automatically creates a key type that simply corresponds to the property names – which is then used in order to encode to/decode from a single keyed container. However one really neat … Read more
One option is to use a wrapper type that attempts to decode a given value; storing nil if unsuccessful: struct FailableDecodable<Base : Decodable> : Decodable { let base: Base? init(from decoder: Decoder) throws { let container = try decoder.singleValueContainer() self.base = try? container.decode(Base.self) } } We can then decode an array of these, with your … Read more
If you don’t mind a bit of shifting of data around you could use something like this: extension Encodable { func asDictionary() throws -> [String: Any] { let data = try JSONEncoder().encode(self) guard let dictionary = try JSONSerialization.jsonObject(with: data, options: .allowFragments) as? [String: Any] else { throw NSError() } return dictionary } } Or an … Read more
With some inspiration from this gist I found, I wrote some extensions for UnkeyedDecodingContainer and KeyedDecodingContainer. You can find a link to my gist here. By using this code you can now decode any Array<Any> or Dictionary<String, Any> with the familiar syntax: let dictionary: [String: Any] = try container.decode([String: Any].self, forKey: key) or let array: … Read more
The list of keys to encode/decode is controlled by a type called CodingKeys (note the s at the end). The compiler can synthesize this for you but can always override that. Let’s say you want to exclude the property nickname from both encoding and decoding: struct Person: Codable { var firstName: String var lastName: String … Read more
You can implement the init(from decoder: Decoder) method in your type instead of using the default implementation: class MyCodable: Codable { var name: String = “Default Appleseed” required init(from decoder: Decoder) throws { let container = try decoder.container(keyedBy: CodingKeys.self) if let name = try container.decodeIfPresent(String.self, forKey: .name) { self.name = name } } } You … Read more