通過segue發送的任何內容返回nil

下面是我在下面的segue的代碼，但是當我嘗試在另一個視圖控制器中訪問它們時，所有變量返回nil。我甚至添加了一個簡單的字符串值發送，並返回零。通過segue發送的任何內容返回nil

extension ViewController : MPMediaPickerControllerDelegate { 
// must implement these, as there is no automatic dismissal 

func mediaPicker(mediaPicker: MPMediaPickerController!, didPickMediaItems mediaItemCollection: MPMediaItemCollection!) { 

    let ViewControllerhost:ViewControllerHost = storyboard?.instantiateViewControllerWithIdentifier("HostViewController") as! ViewControllerHost 

    let representativeItem = mediaItemCollection.representativeItem 
    let title = representativeItem.title 
    let artistName = representativeItem.artist 

    segueInfo = 
     [ "representativeItem": representativeItem 
      , "title": title 
      , "artistName": artistName ] 

    var albumCover = "\(MPMediaItemArtwork())" 
    var songInfo = "\(MPMediaItem())" 
    var messageDict = [albumCover, songInfo] 

    //This sends across Album Artwork, Info, and the duration is sent from the Host view controller 
    let messageData = NSJSONSerialization.dataWithJSONObject(messageDict, options: NSJSONWritingOptions.PrettyPrinted, error: nil) 

    var error:NSError? 

    appDelegate.mpcHandler.session.sendData(messageData, toPeers: appDelegate.mpcHandler.session.connectedPeers, withMode: MCSessionSendDataMode.Unreliable, error: &error) 

    if error != nil{ 
     println("error: \(error?.localizedDescription)") 
    } 

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

     if let nextVC = segue.destinationViewController as? ViewControllerHost 
      , let sender = sender as? ViewController { 
       /*nextVC.representativeItem_ = sender.segueInfo["representativeItem"] as? MPMediaItem 
       nextVC.title_ = sender.segueInfo["title"] as! String 
       nextVC.artistName_ = sender.segueInfo["artistName"] as! String*/ 
       nextVC.representativeItem_ = representativeItem 
       nextVC.title_ = title 
       nextVC.artistName_ = artistName 
       nextVC.test_ = test 
     } 
    } 

    dismissViewControllerAnimated(true, completion: { 
     self.navigationController?.pushViewController(ViewControllerhost, animated: true) 
    }) 
} 








func mediaPickerDidCancel(mediaPicker: MPMediaPickerController!) { 
    self.dismissViewControllerAnimated(true, completion: nil) 

}

}

來源

2015-08-19 Matt Carlson

你確定你的'if let nextVC = segue.destinationViewController as？ ViewControllerHost，讓發件人=發件人爲？ ViewController {'條件正在執行？我必須檢查，但'發送者'可能不是類型的ViewController ... –

我同意@LyndseyScott - 你有兩個可選的綁定那裏，可能會失敗。你是否設置了一個斷點來確認if中的代碼執行？ – Paulw11

我懷疑這個條件失敗：

if let nextVC = segue.destinationViewController as? ViewControllerHost, let sender = sender as? ViewController {

特別是if let sender = sender as? ViewController {部分。

根據docs，sender是觸發segue的按鈕或視圖。這不是視圖控制器本身，所以if let sender = sender as? ViewController {可能會返回false。

來源

2015-08-19 00:24:58

不是100％肯定，如果這有助於但是這是我使用

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

    if segue.identifier == "showTaskDetail" { 
     let detailVC: TaskDetailViewController = segue.destinationViewController as! TaskDetailViewController 
     let indexPath = self.tableView.indexPathForSelectedRow() 
     let thisTask = fetchedResultsController.objectAtIndexPath(indexPath!) as! TaskModel 
     detailVC.detailTaskModel = thisTask 
     detailVC.delegate = self 

    } 
    else if segue.identifier == "showTaskAdd" { 
     let addTaskVC:AddTaskViewController = segue.destinationViewController as! AddTaskViewController 
     addTaskVC.delegate = self 
    } 
}

當你在故事板上點擊下去的塞格斯下的屬性給他們一個標識符

也許試試這個方法？讓我知道，如果它不工作

來源

2015-08-19 00:20:42

我想你錯過了這一點： self.performSegueWithIdentifier（segweId，發件人：個體經營）

來源

2015-08-19 00:23:21 mkwilfreid

通過segue發送的任何內容返回nil

回答

相關問題