We use override when we want to add some features to our method from super class.
If you create a class and implement UIViewcontroller as superclass.UIViewController has predefine method such as viewDidload, viewWillAppear,viewDidDisapear and others. If you want to add some features to superclass methods you should use override prefix. Override is used when you implement method of superclass and add your code.
For example
class Student{
func address(){
var add1 = "drn"
}
func phoneNumber(){
var no = 9806569690
}
}
//create another class and add student as superclass
class Classroom: Student{
//here address is method from superclass student so i am using override prefix
override func address(){
var add2 = "ktm"
}
}
Actuctually i am typing from mobile phone. So i could not give you good example.