使用 Swift 4 中的 JSONDecoder，缺少的键可以使用默认值而不是可选属性吗

Swift 4 added the new Codable protocol. When I use JSONDecoder it seems to require all the non-optional properties of my Codable class to have keys in the JSON or it throws an error.

Making every property of my class optional seems like an unnecessary hassle since what I really want is to use the value in the json or a default value. (I don't want the property to be nil.)

Is there a way to do this?

class MyCodable: Codable {
    var name: String = "Default Appleseed"
}

func load(input: String) {
    do {
        if let data = input.data(using: .utf8) {
            let result = try JSONDecoder().decode(MyCodable.self, from: data)
            print("name: \(result.name)")
        }
    } catch  {
        print("error: \(error)")
        // `Error message: "Key not found when expecting non-optional type
        // String for coding key \"name\""`
    }
}

let goodInput = "{\"name\": \"Jonny Appleseed\" }"
let badInput = "{}"
load(input: goodInput) // works, `name` is Jonny Applessed
load(input: badInput) // breaks, `name` required since property is non-optional