ios - 如何在 Swift 的另一个类中设置变量值

Question

如何在 swift 中从另一个类 myClass 向类 myClass2 中的变量添加值？

我已经尝试过类似 myClass2().myvariable = "value" 的方法，但这没有用；我的变量值仍然是 nil。这是代码:

我的 View Controller 2:

import UIKit

class MyViewController2: UIViewController {

    var myVariable : String?;

    @IBOutlet weak var display: UITextField!

    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    @IBAction func showPressed(sender: AnyObject) {
        display.text = myVariable;
    }

}

View Controller :

import UIKit

class ViewController: UIViewController {

    let myClassInstance = myViewController2();
    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    @IBAction func toView2Pressed(sender: AnyObject) {

        let view2 = self.storyboard?.instantiateViewControllerWithIdentifier("view2") as myViewController2;
        self.navigationController?.pushViewController(view2, animated: true);
        myClassInstance.myVariable = "my new value";
    }

}

Answer 1

您正在创建一个名为 myClass 实例的 myViewController2 实例，但这不是您压入堆栈的实例——被压入的实例是 view2。所以 toView2Pressed 的最后一行应该是，

view2.myVariable = "my new value"

您应该删除该行，let myClassInstance = myViewController2()。它毫无用处。您还应该以大写字母开头您的类(class)名称。