ios - 将数据传递给 TabBar Controller

Question

我想在两个 ViewController 之间传递数据并抛出 TabBarController。 在第一个 ViewController 中，我找到了 textField 和按钮。 在第二个里面我找到了标签。 当我在 textField 中写入一些文本并按下按钮时，我希望该文本出现在第二个 ViewController 的标签中。但是没有任何反应。

还有我的代码:

第一个 View Controller :

import UIKit

class FirstViewController: UIViewController {
    @IBOutlet weak var textField: UITextField!

    @IBAction func enter(_ sender: Any) {
        if textField.text != "" {
            if let window = UIApplication.shared.delegate?.window, let tabBarController = window?.rootViewController as? UITabBarController, let second = tabBarController.viewControllers?.first as? SecondViewController {
                second.label.text = textField.text
                tabBarController.selectedIndex = 0
            }
        }
    }

    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {

    }

    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.
    }


}

第二个 View Controller :

import UIKit

class SecondViewController: UIViewController {

    @IBOutlet weak var label: UILabel!
    var myString = String()

    override func viewDidLoad() {
        super.viewDidLoad()

        label.text = myString
        // 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.
    }


}

Answer 1

我觉得问题出在

tabBarController.viewControllers?.first as? SecondViewController

您可能想这样做:

tabBarController.viewControllers?[1] as? SecondViewController

不要忘记数组是从 0 开始索引的，所以 viewControllers?[1] 实际上返回数组中的第二个元素。