26.6 Storing Custom Types

The @AppStorage and @SceneStorage property wrappers only allow values of certain types to be stored. Specifically Bool, Int, Double, String, URL and Data types. This means that any other type that needs to be stored must first be encoded as a Swift Data object in order to be stored and subsequently decoded when retrieved.

Consider, for example, the following struct declaration and initialization:

struct UserName {

    var firstName: String

    var secondName: String

}

 

var username = UserName(firstName: "Mark", secondName: "Wilson")

Because UserName is not a supported type, it is not possible to store our username instance directly into app or scene-based storage. Instead, the instance needs to be encoded and encapsulated into a Data instance before it can be saved. The exact steps to perform the encoding and decoding will depend on the type of the data being stored....