Making a Swift application

The first step in creating a good application architecture is to create the application itself. We will be creating an iOS journal application used to make daily notes. We are not going to cover any iOS-specific topics, so you can use the same code and create OS X applications as well.

Go ahead! Open Xcode and create a new iOS single-view project application. Now, we are ready for coding.

First, let's create a Person type, for the owner of the journal, and a journal entry type. We will use the Class type to create both Person and JournalEntry. Both classes are very simple—just a bunch of properties and an initializer:

class Person {
  var firstName: String
  var lastName: String

  init (firstName: String, lastName: String) {
    self.firstName = firstName
    self.lastName = lastName
  }
 }

class JournalEntry {
  var title: String
  var text: String
  var date: NSDate
  
  init (title: String, text: String) {
    self.title = title
    self.text =...