Implementing Codable for ARAnchor: “cannot be automatically synthesized in an extension…”

Question

The code extension ARAnchor: Codable {} produces the error:

\"Implementation of \'Decodable\' cannot be automatically synthesized in an extension in a d

Answer 1

Since Codable is a type alias for the Encodable and Decodable protocols, when you use it as a type or a generic constraint, it matches any type that conforms to both protocols:

public typealias Codable = Decodable & Encodable

At the moment (Xcode 10.2.1 / Swift 5.0.1) Codable currently isn't supported yet if an extension in one file adds conformance in a different file. Check this out at https://bugs.swift.org/.

Hope this helps.