在选项卡栏视图控制器内执行操作后应用程序崩溃

Question

我有一个带有标签栏控制器的应用程序。在一个选项卡内有一个导航控制器，它有一个 ViewController。现在这个视图包含一个消息传递界面，我的问题是随着标签栏的添加，我在视图底部的文本框被截断了。为了解决这个问题，我做了一些研究并简单地添加了一行：

self.edgesForExtendedLayout = .None

解决了问题。我的文本框正在显示，用户可以 select 它并对其进行修改等。但是当用户点击发送时，我的应用程序崩溃并显示消息：

fatal error: unexpectedly found nil while unwrapping an Optional value

我不知道问题出在哪里，因为在那之前一切正常...

我的ViewController的全部代码如下：

    class ChatViewController: JSQMessagesViewController, CLLocationManagerDelegate {

    // MARK: Properties

    //Location
    var city: String = ""
    var state: String = ""
    var country: String = ""
    var locationManager = CLLocationManager()
    var locationId: String = ""

     func getLocation() -> String {
        if city == ("") && state == ("") && country == (""){
            return "Anonymous"
        }
        else {
            if country == ("United States") {
                return self.city + ", " + self.state
            }
            else {
                return self.city + ", " + self.state + ", " + self.country
            }
        }
     }

    //Firebase
    var rootRef = FIRDatabase.database().reference()
    var messageRef: FIRDatabaseReference!
    var locationRef: FIRDatabaseReference!

    //JSQMessages
    var messages = [JSQMessage]()

    var outgoingBubbleImageView: JSQMessagesBubbleImage!
    var incomingBubbleImageView: JSQMessagesBubbleImage!



    override func viewDidLoad() {
        super.viewDidLoad()

        self.edgesForExtendedLayout = .None

        locationManager.delegate = self
        locationManager.requestWhenInUseAuthorization()

        if CLLocationManager.locationServicesEnabled() {
            //collect user's location
            locationManager.desiredAccuracy = kCLLocationAccuracyThreeKilometers
            locationManager.requestLocation()
            locationManager.startUpdatingLocation()
        }

        title = "Group Chat"
        setupBubbles()
        // No avatars
        collectionView!.collectionViewLayout.incomingAvatarViewSize = CGSizeZero
        collectionView!.collectionViewLayout.outgoingAvatarViewSize = CGSizeZero

        // Remove file upload icon
        self.inputToolbar.contentView.leftBarButtonItem = nil;

        messageRef = rootRef.child("messages")
        locationRef = rootRef.child("locations")
    }

    override func viewDidAppear(animated: Bool) {
        super.viewDidAppear(animated)
        observeMessages()
    }

  override func viewDidDisappear(animated: Bool) {
    super.viewDidDisappear(animated)
  }


    func locationManager(manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
        //--- CLGeocode to get address of current location ---//
        CLGeocoder().reverseGeocodeLocation(manager.location!, completionHandler: {(placemarks, error)->Void in

            if let pm = placemarks?.first
            {
                self.displayLocationInfo(pm)
            }

        })

    }


    func displayLocationInfo(placemark: CLPlacemark?)
    {
        if let containsPlacemark = placemark
        {
            //stop updating location
            locationManager.stopUpdatingLocation()

            self.city = (containsPlacemark.locality != nil) ? containsPlacemark.locality! : ""
            self.state = (containsPlacemark.administrativeArea != nil) ? containsPlacemark.administrativeArea! : ""
            self.country = (containsPlacemark.country != nil) ? containsPlacemark.country! : ""

            print(getLocation())

        }

    }


    func locationManager(manager: CLLocationManager, didFailWithError error: NSError) {
        print("Error while updating location " + error.localizedDescription)
    }


    override func collectionView(collectionView: JSQMessagesCollectionView!,
                                 messageDataForItemAtIndexPath indexPath: NSIndexPath!) -> JSQMessageData! {
        return messages[indexPath.item]
    }

    override func collectionView(collectionView: JSQMessagesCollectionView!,
                                 messageBubbleImageDataForItemAtIndexPath indexPath: NSIndexPath!) -> JSQMessageBubbleImageDataSource! {
        let message = messages[indexPath.item] // 1
        if message.senderId == senderId { // 2
            return outgoingBubbleImageView
        } else {
            return incomingBubbleImageView
        }
    }

    override func collectionView(collectionView: UICollectionView,
                                 numberOfItemsInSection section: Int) -> Int {
        return messages.count
    }

    override func collectionView(collectionView: JSQMessagesCollectionView!,
                                 avatarImageDataForItemAtIndexPath indexPath: NSIndexPath!) -> JSQMessageAvatarImageDataSource! {
        return nil
    }

    private func setupBubbles() {
        let factory = JSQMessagesBubbleImageFactory()
        outgoingBubbleImageView = factory.outgoingMessagesBubbleImageWithColor(
            UIColor.jsq_messageBubbleBlueColor())
        incomingBubbleImageView = factory.incomingMessagesBubbleImageWithColor(
            UIColor.jsq_messageBubbleLightGrayColor())
    }

    func addMessage(id: String, text: String) {
        let message = JSQMessage(senderId: id, displayName: "", text: text)

        messages.append(message)
    }

    override func collectionView(collectionView: UICollectionView,
                                 cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
        let cell = super.collectionView(collectionView, cellForItemAtIndexPath: indexPath)
            as! JSQMessagesCollectionViewCell

        let message = messages[indexPath.item]

        if message.senderId == senderId {
            cell.textView!.textColor = UIColor.whiteColor()
        } else {
            cell.textView!.textColor = UIColor.blackColor()
        }

        return cell
    }

    override func didPressSendButton(button: UIButton!, withMessageText text: String!, senderId: String!,
                                     senderDisplayName: String!, date: NSDate!) {

        let itemRef = messageRef.childByAutoId()
        let messageItem = [
            "text": text,
            "senderId": senderId
        ]
        itemRef.setValue(messageItem)

        let locRef = locationRef.childByAutoId()
        let locItem = [
            senderId : [
                "location": getLocation()
            ]
        ]

        locRef.setValue(locItem)

        // Retrieve data from Firebase Realtime database

        FIRDatabase.database().reference().child("locations").child(senderId).child("location").observeSingleEventOfType(.Value, withBlock: { (snapshot) in
            self.locationId = snapshot.value!["location"] as! String
        }) { (error) in
            print(error.localizedDescription)
        }


        JSQSystemSoundPlayer.jsq_playMessageSentSound()

        finishSendingMessage()

    }

    private func observeMessages() {

        let messagesQuery = messageRef.queryLimitedToLast(25)

        messagesQuery.observeEventType(.ChildAdded) { (snapshot: FIRDataSnapshot!) in

            let id = snapshot.value!["senderId"] as! String
            let text = snapshot.value!["text"] as! String

            self.addMessage(id, text: text)

            self.finishReceivingMessage()
        }
    }


    override func textViewDidChange(textView: UITextView) {
        super.textViewDidChange(textView)
    }


    override func collectionView(collectionView: JSQMessagesCollectionView!, attributedTextForCellBottomLabelAtIndexPath indexPath: NSIndexPath!) -> NSAttributedString! {

        let message = messages[indexPath.item]

        // Call data I have retrieved below with message 
        let text = "From: " + locationId

        if message.senderId == senderId {
            return nil
        } else {
            return NSAttributedString(string: text)
        }

    }

    override func collectionView(collectionView: JSQMessagesCollectionView, layout collectionViewLayout: JSQMessagesCollectionViewFlowLayout, heightForCellBottomLabelAtIndexPath indexPath: NSIndexPath) -> CGFloat {
        return kJSQMessagesCollectionViewCellLabelHeightDefault
    }


}

提前感谢您的帮助！

Answer 1

问题发生在用户点击发送按钮后。我刚刚将行 self.edgesForExtendedLayout = .None 添加到特定操作中，它运行良好！

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