静态和懒惰变量：类似的行为？

Question

将'dateFormatter'评估一次，就像懒惰一样？

class Birthday {

  private static var dateFormatter: DateFormatter = {
    let formatter = DateFormatter()
    formatter.locale = Locale(identifier: "en_US_POSIX")
    formatter.dateFormat = "d MMMM yyyy"
    return formatter
  }()

  private let date: Date

  init(date: Date) {
    self.date = date
  }

}

ASDF