Using SwiftUI AppStorage to cache Codable entities

JSONStringRawRepresentable.swift

import Foundation

struct JSONStringRawRepresentable<T: Codable>: RawRepresentable {
    typealias RawValue = String

    var value: T

    init(value: T) {
        self.value = value
    }

    init?(rawValue: String) {
        guard let data = rawValue.data(using: .utf8),
              let result = try? JSONDecoder().decode(T.self, from: data) else { return nil }

        self = .init(value: result)
    }

    var rawValue: String {
        guard let data = try? JSONEncoder().encode(value),
              let result = String(data: data, encoding: .utf8) else {
            return String()
        }

        return result
    }
}

YourView.swift

struct Foo: Codable {
 // ...
}

struct YourView: View {
  typealias CachedFoo = JSONStringRawRepresentable<[Foo]>
  
  @AppStorage("cachedFoo") var cachedFoo: CachedFoo = .init(value: [])
  
  var body: some View {
    // Make a list from your cached Stuff
    List(cachedFoo.value, id: \.self) { foo in 
      Text(foo)
    } 
  }
}