在Swift中将值从一个视图控制器传递到另一个视图控制器

问题描述

我正在研究Swift，我在tableview的didSelectRowAtIndexPath方法中遇到了错误。
我想将值传递给另一个视图控制器，即'secondViewController'。这里EmployeesId是一个数组。相关代码如下：

I am working on Swift, I've got an error in tableview's didSelectRowAtIndexPath method.I want to pass a value to another view controller i.e 'secondViewController'. Here EmployeesId is an Array. The relevant code is as follows:

func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
    var view: Dashboard = self.storyboard?.instantiateViewControllerWithIdentifier("Dashboard") as Dashboard

    self.navigationController?.pushViewController(view, animated: true)
    secondViewController.UserId = employeesId[indexPath.item]  //getting an error here.
}

但我收到此错误：
致命错误：意外发现在解包可选值时为零。

But I am getting this Error: fatal error: unexpectedly found nil while unwrapping an Optional value.

任何帮助都将受到赞赏。

Any help will be appreciated.

推荐答案

这是一个有两个假设的一般解决方案。首先，UserId不是UILabel。其次，你打算使用在第二行实例化的 view ，而不是使用 secondViewController

Here's a general solution with two assumptions. First, UserId is not a UILabel. Second, you meant to use view which was instantiated in the second line, instead of using secondViewController

override func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
    var view: Dashboard = self.storyboard?.instantiateViewControllerWithIdentifier("Dashboard") as Dashboard

    self.navigationController?.pushViewController(view, animated: true)
    view.UserId = employeesId[indexPath.row]
}

这是Dashboard的样子：

Here's what Dashboard looks like:

class Dashboard: UIViewController {
    var UserId: String!
    @IBOutlet var userIDLabel: UILabel!

    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.
        userIDLabel.text = UserId
    }

    ...
}

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