SOLVED: What's the container for and what's it doing?

@vtabmow

Feb '22

Can someone explain what the point of the container is in the encode method and the initializer? I know we need it, because Paul said we do, but I don't really understand what it does. I looked up the Apple documentation and I didn't find the description there to be all that helpful.

class MyClass: ObservableObject, Codable {
    enum CodingKeys: CodingKey {
        case name
    }
    @Published var name = ""

    func encode(to encoder: Encoder) throws {
        var container = encoder.container(keyedBy: CodingKeys.self)

        try container.encode(name, forKey: .name)
    }

    init() {}

    required init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)

        name = try container.decode(String.self, forKey: .name)
    }
}

@Adnano99

Feb '22

sad to find no answer yet :(

did you find an answer yourself?

@Greenamberred HWS+

Feb '22

Which container are you referring to?

var container = encoder.container(keyedBy: CodingKeys.self)
try container.encode(name, forKey: .name)

var container

is there to create a shorthand version (substitution) of the full declaration, so that it could easily be use many times. Here it is used only once with .encode. It is a convenience. Otherwise the full version of the next line is

try encoder.container(keyedBy: CodingKeys.self).encode(name, forKey: .name)

encoder.container

is using a method .container for the Encoder protocol.

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