golf-course-model.swift

struct Hole {
  let length: Int
  let number: Int
  let par: Int
}

struct GolfCourse {
  let name: String
  let holes: [Hole]
}

golf-course.json

{
  "name": "My Course",
  "holes": [
    {
      "number": 1,
      "length": 143,
      "par": 3
    },
    {
      "number": 2,
      "length": 340,
      "par": 4
    }
  ]
}

JSON and the arguments.md

Code snippets for the blog post "JSON and the arguments" at http://www.apokrupto.com/blog-1/2016/4/3/json-and-the-arguments

model-initialisers-1.swift

typealias JSONFormat = [String: AnyObject]

extension Hole {
  typealias Format = JSONFormat
  
  init?(_ holeInfo: Format) {
    guard let length = holeInfo["length"] as? Int, let number = holeInfo["number"] as? Int, let par = holeInfo["par"] as? Int else {
      return nil
    }
    
    self.length = length
    self.number = number
    self.par    = par
  }
}

extension GolfCourse {
  typealias Format = JSONFormat
  
  init?(_ courseInfo: Format) {
    guard let name = courseInfo["name"] as? String,
        let holeInfo = courseInfo["holes"],
        let holes = (holeInfo as? [Hole.Format])?.flatMap({ Hole($0) }) where holes.count == holeInfo.count else {
          return nil
    }
    
    self.name  = name
    self.holes = holes
  }
}

model-initialisers-2.swift

extension Hole {
  typealias Format = [String: Int]
  
  init?(_ holeInfo: Format) {
    guard let length = holeInfo["length"], let number = holeInfo["number"], let par = holeInfo["par"] else {
      return nil
    }
    
    self.length = length
    self.number = number
    self.par    = par
  }
}

wishful-thinking.swift

protocol JSONType {
}

extension NSString:     JSONType {}
extension NSNumber:     JSONType {}
extension NSArray:      JSONType {}
extension NSDictionary: JSONType {}

typealias JSONFormat= [String: JSONType]