准备转至 UITabBarController 选项卡

Question

我想将信息从 ViewController 传递到 UITabBarController 以便我可以从 UITabBarController 的第三个选项卡中的视图控制器访问某些信息。

但是，问题是当我尝试这样做时我的程序总是崩溃。到目前为止，这是我的代码：

我这样调用 segue:

self.firstName = user.first_name
self.lastName = user.last_name
self.performSegueWithIdentifier("OffersView", sender: self)

然后我覆盖了 prepareForSegue 函数，这样我就可以像这样在这个函数中传递信息：

override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
    if(segue.identifier == "OffersView"){
        let barViewControllers = segue.destinationViewController as UITabBarController
        let destinationViewController = barViewControllers.viewControllers![2] as ProfileController
        destinationViewController.firstName = self.firstName
        destinationViewController.lastName = self.lastName
    }
}

当我尝试设置 destinationViewController（在上面代码的第二行）时，我的代码崩溃了。我不确定为什么，因为我查看了许多 Whosebug 帖子，例如

Swift tab bar view prepareforsegue and Pass data from tableview to tab bar view controller in Swift.但没有太大的成功。我可能需要创建一个 UITabBarControllerDelegate class 并通过它传递信息吗？任何提示将不胜感激。谢谢！

Answer 1

讨论后发现问题是tab bar controller的children嵌入到navigation controller中，所以代码需要改成这样，

override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) { 
    let barViewControllers = segue.destinationViewController as! UITabBarController 
    let nav = barViewControllers.viewControllers![2] as! UINavigationController 
    let destinationViewController = nav.topviewcontroller as ProfileController 
    destinationViewController.firstName = self.firstName
    destinationViewController.lastName = self.lastName 
}

Answer 2

在 swift 3, xcode 8 中，代码会像

let barViewControllers = segue.destination as! UITabBarController
let nav = barViewControllers.viewControllers![0] as! UINavigationController
let destinationViewController = nav.viewControllers[0] as! YourViewController
        destinationViewController.varTest = _varValue

Answer 3

Swift 4 没有强制可选展开的解决方案

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if let barVC = segue.destination as? UITabBarController {
        barVC.viewControllers?.forEach {
            if let vc = [=10=] as? YourViewController {
                vc.firstName = self.firstName
                vc.lastName = self.lastName
            }
        }
    }
}

准备转至 UITabBarController 选项卡

Prepare for Segue to UITabBarController Tab

iphone

ios

segue

swift