Classes can define properties that instances of the class can use. In this example, Dog has two properties: name and dogYearAge:

class Dog {
    var name = ""
    var dogYearAge = 0
}

You can access the properties with dot syntax:

let dog = Dog()
print(dog.name)
print(dog.dogYearAge)

Classes can also define methods that can be called on the instances, they are declared similar to normal functions, just inside the class:

class Dog {
    func bark() {
        print("Ruff!")
    }
}

Calling methods also uses dot syntax:

dog.bark()