在Swift中初始化类实例和访问变量

Question

I just created a class and gave it some vars. Unfortunately I can't access these variables in my iOS-Projects . However, the same syntax works in playground...

class ViewController: UIViewController 
{
    class Dog 
    {
        var age = 0
        var hungry = TRUE
    }
    var rex = Dog()
    rex.age = 2   //ERROR: EXPECTED DECLARATION
}

Answer 1

The last two lines need to be inside a function. You can have only declarations in class scope, not expressions to be executed.

Answer 2

The syntax for a class declaration is:

class <class name>: <superclass>, <adopted protocols> {
  <declarations>
}

Your declaration of ViewController includes rex.age = 2 which itself is not a declaration , it is a statement - specifically a binary expression with an infix operator.