swift - 如何从方法内部更新类变量，以便该变量对 Swift 中的其他类可见？

Question

// some VC
Class FirstClass: UIViewController {

    var tag = -1 // supposed to represent a tag for a UIView inside of FirstClass

        // supposed to change the tag 
        func abc() {

            tag = 5

        }


        // returns the tag
        func getTag() -> Int {

            return tag

       }
    }


// another VC
Class SecondClass: UIViewController {

    FirstClass().abc()
    var a = FirstClass().getTag() // prints -1; I want it to print 5
    let someView = view.viewWithTag(a) as! UIView // nil

}

我想从函数内部更新“tag”变量。为了简单起见，我省略了一些基本函数，例如“viewDidLoad”。 谢谢!

Answer 1

像这样更改 SecondClass 中的代码:

Class SecondClass: UIViewController {

      let myfirstClass = FirstClass()
      myFirstClass.abc()     // changes the tag in your instance of FirstClass

      var a = myfirstClass.getTag()

      // will print 5 because now you ask the instance, 
      // where the abc-function was called       
}