Swift Tutorial - Swift Inheritance

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Classes have the ability to inherit methods and properties from a parent class.

class Person {
    var name: String = "Name"
    var age:Int = 0

    func profile() -> String {
        return "I'm \(self.name) and I'm \(self.age) years old."
    }
}

class Employee: Person {

}

In the code above, Employee is inheriting from Person.

To indicate what class to inherit, add a colon : and the name of the parent class.

Example

The following code adds more properties or methods to the new class.

class Employee: Person {
    var employeeNumber = 9
    var hourlyRate = 12.00
}

var e1 = Employee()
e1.name = "Jack"
e1.age = 38
e1.employeeNumber = 1
e1.hourlyRate = 10.50

Overriding Methods and Properties

When inheriting a class, we can change how the parent class methods and properties behave by overriding them.

The following code shows how to override Methods.

class Person {
    var name: String = "Name"
    var age:Int = 0
    func profile() -> String {
        return "I'm \(self.name) and I'm \(self.age) years old."
    }
}

class Employee: Person {
    var employeeNumber = 1234567890
    var hourlyRate = 12.00
    override func profile() -> String {
        return "I'm \(self.name) and my hourly rate is $\(self.hourlyRate)"
    }

}

var p1 = Person()

p1.name = "Jack"
p1.age = 40

println(p1.profile())

var e1 = Employee()

e1.name = "Jodd"
e1.age = 18
e1.employeeNumber = 1
e1.hourlyRate = 45.55

println(e1.profile())

Override Properties

We can also override property declarations.

The following code shows how to override properties.

class Person {
    var name: String = "Name"
    var age:Int = 0
    func profile() -> String {
        return "I'm \(self.name) and I'm \(self.age) years old."
    }

    var lastName:String {
       get {
           return "NoName"
       }
       set {
           _lastName = newValue
       }
    }    
}
class Employee: Person {
    var employeeNumber = 2
    var hourlyRate = 12.00


    override var lastName:String {
       get {
           return "Anonymous"
       }
       set {
           _lastName = newValue
       }
    }

}

var p1 = Person()
p1.lastName = "A"

var e1 = Employee()
e1.lastName = "B"

println(p1.lastName)
println(e1.lastName)

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