Swift Codable Examples

Codable was implemented in Swift 4, and made available starting in Xcode 9.0.

For more history details, see swift evolution: SE-0166

Codable

public typealias Codable = Decodable & Encodable

Decodable

public protocol Decodable {
    public init(from decoder: Decoder) throws
}

Encodable

public protocol Encodable {
    public func encode(to encoder: Encoder) throws
}

Supported File Formats

• JSON
• Property List (.plist)

JSON Examples

Simple

{
  "first": "Steve",
  "last": "Dave"
}

• Implementation: Name.swift, AnotherName.swift
• Tests: NameTests.swift, AnotherNameTests.swift

{
  "name": "Gizmo",
  "kind": "dog",
  "age": 14,
  "isFriendly": true
}

• Implementation: Pet.swift
• Tests: PetTests.swift

Nested

{
  "age": 45,
  "name": {
    "first": "Steve",
    "last": "Dave"
  }
}

• Implementation: Person.swift
• Tests: PersonTests.swift

Array

{
  "strings": ["Red", "Green", "Blue"],
  "numbers": [1, 3, 5, 7, 9],
  "bools": [true, true, false]
}

• Tests: ArrayTests.swift, NameTests.swift

Common

{
  "first-name": "Steve",
  "last-name": "Dave"
}

• Implementation: Contact.swift
• Tests: ContactTests.swift

Tuple

{
  "dimension": [ 16, 9 ]
}

• Implementation: Size.swift
• Tests: SizeTests.swift

Hierarchy

{
  "shipping-address": {
    "name": "Detroit Labs",
    "city": "Detroit",
    "state": "MI"
  },
  "billing-address": {
    "name": "Paula Goodski",
  },
  "items": [
    { "sku": "I001", "name": "Labs Beats V1", "quantity": 10000 }
  ]
}

• Implementation: Invoice.swift, Address.swift, Item.swift
• Tests: InvoiceTests.swift

Inheritance

{
  "cat": {
    "name": "Fluffy",
    "lenghtOfTail": 6
  },
  "dog": {
    "name": "Skippy",
    "numberOfBones": 1
  }
}

• Implementation: Animal.swift, Cat.swift, Dog.swift
• Tests: AnimalTests.swift, CatTests.swift, DogTests.swift

Option Set

{
  "sports": [ "swimming", "running" ]
}

• Implementation: Sports.swift
• Tests: SportsTests.swift

Inconvenient Array

{
  "item.3": "Delta",
  "item.0": "Alfa",
  "item.2": "Charlie",
  "item.1": "Bravo"
}

• Implementation: InconvenientArray.swift
• Tests: InconvenientArrayTests.swift

Date With Time (ISO8601)

{
  "origin": "Atlanta, GA",
  "departure": "2019-03-28T08:15:02Z",
  "destination": "Detroit, MI",
  "arrival": "2019-04-01T18:45:20Z"
}

• Implementation: Trip.swift
• Tests: TripTests.swift

Date Without Time

{
  "origin": "Atlanta, GA",
  "departure": "2019-03-28",
  "destination": "Detroit, MI",
  "arrival": "2019-04-01"
}

• Implementation: Trip.swift
• Tests: TripTests.swift

Empty Collection

{
  "mother": {
    "first-name": "Anne",
    "last-name": "Dave"
  },
  "father": {
    "first-name": "Steve",
    "last-name": "Dave"
  },
  "brother": {
  }
}

• Resources: NilOnEmpty.swift, RawCodingKeys.swift
• Implementation: AnotherFamily.swift, CorruptFamily.swift, Family.swift
• Tests: AnotherFamilyTests.swift, CorruptFamilyTests.swift

Enum with Associated Values

[
  {
    "bicycle": {}
  },
  {
    "boat": {
      "floats": true
    }
  },
  {
    "car": {
      "year": 2016,
      "make": "Tesla",
      "model": "Model S"
    }
  },
  {
    "limo": {
      "_0": "Black",
      "something": true,
      "_2": 8
    }
  },
  {
    "truck": {
      "wheels": 18
    }
  },
  {
    "van": {
      "contents": ["Wrench", "Hammer"]
    }
  }
]

• Resources: Vehicle.swift
• Tests: VehicleTests.swift

Safe Decodable

[
  {
    "sku": "I001",
    "name": "Labs Beats V1",
  },
  {
    "sku": "I002",
    "name": "Labs Beats V2",
    "quantity": 8
  }
]

• Resources: SafeDecodable.swift
• Tests: SafeDecodableTests.swift

Decode Shorthand

{
  "name": "Office Space",
  "address": "123 Main St"
}

• Resources: KeyedDecodingContainer.swift
• Implementation: Building.swift
• Tests: BuildingTests.swift

Property List Examples

Simple

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
  <dict>
    <key>first</key>
    <string>Steve</string>
    <key>last</key>
    <string>Dave</string>
  </dict>
</plist>

• Implementation: Name.swift
• Tests: NameTests.swift

Nested

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
  <dict>
    <key>age</key>
    <integer>45</integer>
    <key>name</key>
    <dict>
      <key>first</key>
      <string>Steve</string>
      <key>last</key>
      <string>Dave</string>
    </dict>
  </dict>
</plist>

• Implementation: Person.swift
• Tests: PersonTests.swift