In the previous exercise, we’ve supplied our instances’ properties with default values. However, if we know that our class instances vary a lot from one to another, we can include an init() method for customization. The following syntax is used for an init() method:

class className {
  var property = value
  init (property: valueType) {
     self.property = property
  }
}

The init() method is special since it doesn’t require the func keyword and gets called upon instance creation. Another unique feature is that the init() method uses the self keyword to reference itself.

Let’s see the init() in action:

class Student {
  var name = ""
  var year = 0
  var gpa = 0.0
  var honors = false

  init(name: String, year: Int, gpa: Double, honors: Bool) {
    self.name = name
    self.year = year
    self.gpa = gpa
    self.honors = honors
  }
}

So now we can create an instance of the Student class and initialize its properties in one line:

var bart = Student(name: "Bart Simpson", year: 4, gpa: 0.0, honors: false)

Note that all properties must have arguments and the ordering of the params must match the ordering of the declared properties.