let defaults = UserDefaults.standard
defaults.set(25, forKey: "Age")
defaults.set(true, forKey: "UseTouchID")
defaults.set(CGFloat.pi, forKey: "Pi")

• [ ] How to save custom class to UserDefaults

  1. Make class conform to NSCoding

  class Person: NSObject, NSCoding {
      var name: String
      var image: String
      
      init(name: String, image: String){
          self.name = name
          self.image = image
      }
      
      // When loading
      required init?(coder: NSCoder) {
          name = coder.decodeObject(forKey: "name") as? String ?? ""
          image = coder.decodeObject(forKey: "image") as? String ?? ""
      }
      
      // When saving
      func encode(with coder: NSCoder) {
          coder.encode(name, forKey: "name")
          coder.encode(image, forKey: "image")
      }
  }
  

  1. OurObject → Data → UserDefaults

  func save(){
          if let savedData = try? NSKeyedArchiver.archivedData(withRootObject: people, requiringSecureCoding: false){
              UserDefaults.standard.set(savedData, forKey: "people")
          }
      }
  

  1. UserDefaults → Data → OurObject

  if let savedPeople = UserDefaults.standard.object(forKey: "people") as? Data{
              if let decodedPoeple = try? NSKeyedUnarchiver.unarchiveTopLevelObjectWithData(savedPeople) as? [Person]{
                  people = decodedPoeple
              }
          }
  

• [ ] Get type from UserDefaults

let shouldDo = defaults.bool(forKey: "ShouldDo")
let complexType = defaults.object(forKey: "UnknownObject")

• [ ] Unwrapping type

let myTable = defaults.object(forKey: "MyTable") as? [String: String] ?? [String: String]()