Programmers familiar with other object-oriented programming languages may be in the habit of prefixing references to properties and methods with self to indicate that the method or property belongs to the current class instance. The Swift programming language also provides the self property type for this purpose and it is, therefore, perfectly valid to write code which reads as follows:
class MyClass {
var myNumber = 1
func addTen() {
self.myNumber += 10
}
}
In this context, the self prefix indicates to the compiler that the code is referring to a property named myNumber which belongs to the MyClass class instance. When programming in Swift, however, it is no longer necessary to use self in most situations since this is now assumed to be the default for references to properties and methods. To quote The Swift...
