在 Swift 中初始化类实例和访问变量
问题描述：
我刚刚创建了一个类并给了它一些变量.不幸的是，我无法在我的 iOS-Projects 中访问这些变量.但是，相同的语法在操场上也有效...
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
}
答
类声明的语法是:
class <class name>: <superclass>, <adopted protocols> {
<declarations>
}
您对 ViewController 的声明包括 rex.age = 2，它本身不是一个声明，而是一个声明 - 特别是带有中缀运算符的二元表达式.
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.