ios - 在 unwind segue 停止 segue 后显示警报。如何确保在 unwind segue 完成后显示警报？

Question

我有一个从 A View Controller 到 B View Controller 的 unwind segue。

在B中做了一个网络操作，操作完成后，响应会显示在A View Controller 中。

我成功制作了这个结构。但是有一个问题:

当我尝试显示警报时，它显示但停止了 segue。我如何确保在 segue 完成后显示警报。

错误在这里:

2016-04-27 14:39:28.350 PROJECT[9100:128844] Presenting view controllers on detached view controllers is discouraged <PROJECT.FeedTableViewController: 0x7a928c00>.
2016-04-27 14:39:28.359 PROJECT[9100:128844] popToViewController:transition: called on <UINavigationController 0x7c12a800> while an existing transition or presentation is occurring; the navigation stack will not be updated.

A 中的展开处理程序:

@IBAction func unwindToFeed(segue: UIStoryboardSegue) {
        jsonArray[rowFromShare!]["ApplicationDataUsers"] = jsonFromShare!
        tableView.reloadData()
        ShowErrorDialog("Success", message: successMessageFromShare!, buttonTitle: "OK")
    }

//Error Dialog
func ShowErrorDialog(title:String, message:String, buttonTitle:String){
    let alert = UIAlertController(title: title, message: message, preferredStyle: .Alert)
    alert.addAction(UIAlertAction(title: "OK", style: .Default) { _ in })
    self.presentViewController(alert, animated: true){}
}

在 B 中展开触发器:

override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {

    if segue.identifier == "unwindToFeed"{
        let feedTable = segue.destinationViewController as! FeedTableViewController
        feedTable.rowFromShare = row
        feedTable.jsonFromShare = jsonToShare
        feedTable.successMessageFromShare = successMessageToShare
    }

    // Get the new view controller using segue.destinationViewController.
    // Pass the selected object to the new view controller.
}

A = FeedTableViewControllerB = ShareTableViewController

如何确保在 segue 完成后显示警报？

Answer 1

如您所见，unwindToFeed 方法在展开转场完成之前被调用。

一种方法是在 unwindToFeed 方法中设置一个 bool 值，然后在您知道转场已完成时在 viewDidAppear 中检查此 bool 值。如果设置了 bool 值，那么您可以显示警报:

@IBAction func unwindToFeed(segue: UIStoryboardSegue) {
    jsonArray[rowFromShare!]["ApplicationDataUsers"] = jsonFromShare!
    tableView.reloadData()
    self.unwinding = true
}

override func viewDidAppear(animated: Bool) {
   super.viewDidAppear(animated)
   if (self.unwinding) {
       self.ShowErrorDialog("Success", message: successMessageFromShare!, buttonTitle: "OK")
   self.unwinding=false
   }