Swift Class Functions

Question

So I am wondering about class functions and "normal instance functions". I would like to know what is the purpose of a class function. Is it just so one can use certain functions without assigning the class to a variable first or does it have other purposes?

class Dog {
    func bark()->String{
        return "Woef Woef!"
    }
    class func bark_class()->String{
        return "Woef Woef!"
    }
}

var dog = Dog()
dog.bark() // Woef Woef!

Dog.bark() // Throws and error
Dog.bark_class() // Woef Woef! > Apparently is doens't need an initiated object

Answer 1

To call your method bark you have to make an instance of the class.

var instance = Dog()

Then you say instance.bark()

You don't need to make an instance when you want to call a class func. Like you said you just can call it with:

Dog.bark_class()

A Class fun is also called a Type Method

Apple docs:

Instance methods, as described above, are methods that are called on an instance of a particular type. You can also define methods that are called on the type itself. These kinds of methods are called type methods. You indicate type methods for classes by writing the keyword class before the method’s func keyword, and type methods for structures and enumerations by writing the keyword static before the method’s func keyword.