@propertyWrapper with optional wrappedValue

optional_wrapper_value.swift

@propertyWrapper
public struct Database<T> {
  
  public let key: String
  public var wrappedValue: T? {
    get { return UserDefaults.standard.object(forKey: key) as? T }
    set { UserDefaults.standard.set(newValue, forKey: key) }
  }

  public init(key: String) {
    self.key = key
  }

  public init(key: String, wrappedValue: T) {
    self.key = key
    self.wrappedValue = wrappedValue
  }
}