斯威夫特（Swift）：在进行当前模态搜索后，IBOutlets为零

Question

Before I begin the segue, all my outlets are not nil, and work fine. However, as soon as the presentation happens, the IBOutlets from the first view controller are nil and my compiler says Unexpectedly found nil while unwrapping an optional value.

I am not using any special presentation or segue, so why is this happening? What code can I show you?

I have timers on the first view controller that are accessing IBOutlets in the first view controller: could this be the problem?

Update: I think my compiler thinks my second view uses the same view controller as the first, and as such all the IBOutlets are nil. I think this because the method viewDidLoad is being called when I do the segue.

Update: You can download my source code here: Source Code

Update: Here is my ViewController.swift

//
//  ViewController.swift
//  SuperCommunication
//
//  Created by Jonathan Grant on 8/10/15.
//  Copyright (c) 2015 VirtuMedHealth. All rights reserved.
//

import UIKit
import Parse
import FontAwesome_swift

class ViewController: UIViewController, UITableViewDataSource, UITableViewDelegate, UITextFieldDelegate
{
    /*Sign In*/
    let me = CurrentAccount(id: "r10010101010100101")

/*Messages and Channels*/
var selectedChannelTimer = NSTimer() //timer to check for new messages
var allChannelsTimer = NSTimer() //Timer to check for new messages in all channels
var selectedChannel: Channel?
var channelList = [Channel]()
@IBOutlet weak var channelsTableView: UITableView!

/*Top Bar*/
@IBOutlet weak var topBarPrivateChat: UIView!
@IBOutlet weak var topBarOtherChat: UIView!
@IBOutlet weak var topNameLabel: UILabel!
@IBOutlet weak var topJobLabel: UILabel!
@IBOutlet weak var topOfficeLabel: UILabel!
@IBOutlet weak var topChannelNameLabel: UILabel!
@IBOutlet weak var topTypeChannelLabel: UILabel!
@IBOutlet weak var topTypeChannelIconLabel: UILabel!
@IBOutlet weak var topNumberPeopleLabel: UILabel!
@IBOutlet weak var topVideoButton: UIButton!
@IBOutlet weak var topVoiceButton: UIButton!

/*UITextFieldDelegate*/
@IBOutlet weak var messageTextField: UITextField!
func textFieldDidBeginEditing(textField: UITextField) {    //delegate method

}

func textFieldShouldEndEditing(textField: UITextField) -> Bool {  //delegate method
    return true
}

func textFieldShouldReturn(textField: UITextField) -> Bool {   //delegate method
    //textField.resignFirstResponder()

    //check if message isn't empty
    if textField.text?.isEmpty == true {

    } else {
        let cm = ChatMessage(message: (textField.text)!, dateSent: NSDate(), userSent: CurrentAccount.user!)
        chatMessages.append(cm)
        //send this message
        sendParseChatMessageObject(cm)
        textField.text = ""
        //reload table data
        tableView.reloadData()
    }

    return true
}

/*UITableViewDataSource*/
@IBOutlet weak var tableView: UITableView!
var chatMessages = [ChatMessage]()
func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
    //code
    if tableView.tag == 1 {
        //then they chose a message
    } else if tableView.tag == 2 {
        //then they chose a channel
        if indexPath.section == 0 {
            //then its easy
            selectedChannel = channelList[indexPath.row]
        } else if indexPath.section == 1 {
            selectedChannel = channelList[indexPath.row + Channel.publicChannels]
        } else {
            //private channel
            selectedChannel = channelList[indexPath.row + Channel.publicChannels + Channel.groupChannels]
        }
        loadMessagesForSelectedChannel()
        if selectedChannel!.tag == 3 {
            setUpTopBarForPrivateChatLabels()
        } else {
            setUpTopBarForOtherChatLabels()
        }
    }
}

func tableView(tableView: UITableView, titleForHeaderInSection section: Int) -> String? {
    if tableView.tag == 1 {
        return ""
    } else {
        if tableView.tag == 2 {
            if section == 0 {
                return "Public (\(Channel.publicChannels))"
            } else if section == 1 {
                return "Group (\(Channel.groupChannels))"
            } else {
                return "Private (\(CurrentAccount.friends.count))"
            }
        }
    }
    return ""
}

func numberOfSectionsInTableView(tableView: UITableView) -> Int {
    if tableView.tag == 1 {
        return 1
    } else if tableView.tag == 2 {
        return 3
    }
    return 1
}

func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    if tableView.tag == 1 {
        return chatMessages.count
    } else if tableView.tag == 2 {
        //return amount of tags for that section
        if section == 0 {
            return Channel.publicChannels
        } else if section == 1 {
            return Channel.groupChannels
        } else {
            return CurrentAccount.friends.count
        }
    }
    return 1
}

func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
    if tableView.tag == 1 {
        let today = NSDate()
        let form = NSDateFormatter()
        form.dateStyle = NSDateFormatterStyle.LongStyle
        form.timeStyle = NSDateFormatterStyle.NoStyle
        if form.stringFromDate(today) == form.stringFromDate(chatMessages[indexPath.item].dateSent!) {
            //then it is today
            var identifier = "chatBox"
            print("\(chatMessages[indexPath.item].userSent!.userID) ~ \(CurrentAccount.user!.userID)")
            if chatMessages[indexPath.item].userSent!.userID == CurrentAccount.user!.userID {
                identifier = "chatBoxMe"
                print("Heuh")
            }
            let cell = tableView.dequeueReusableCellWithIdentifier(identifier, forIndexPath: indexPath) as! ChatMessageTableViewCell

            cell.configureCellWithChatMessage(chatMessages[indexPath.row])

            return cell
        }
        print("\(chatMessages[indexPath.item].userSent!.userID) ~ \(CurrentAccount.user!.userID)")
        var identifier = "chatBoxNotToday"
        if chatMessages[indexPath.item].userSent!.userID == CurrentAccount.user!.userID {
            identifier = "chatBoxNotTodayMe"
            print("Heuh")
        }

        let cell = tableView.dequeueReusableCellWithIdentifier(identifier, forIndexPath: indexPath) as! ChatMessageNotTodayTableViewCell

        cell.configureCellWithChatMessage(chatMessages[indexPath.row])

        return cell
    } else {
        let cell = tableView.dequeueReusableCellWithIdentifier("channelCell") as! UITableViewCell
        if indexPath.section == 2 {
            //private messages
            cell.textLabel?.text = "\(CurrentAccount.friends[indexPath.row].firstName!) \(CurrentAccount.friends[indexPath.row].lastName!)"
        } else {
            var num = 0
            if indexPath.section == 1 {
                num = Channel.publicChannels
            }
            cell.textLabel?.text = "\(channelList[num + indexPath.item].name)"
        }

        return cell
    }
}

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.
    //messageTextField.delegate = self
    setUpTopBarIcons()
    getAllParseChannels()
}

func loadFirstParseChannel() {
    if channelList.count > 0 {
        selectedChannel = channelList[0]
        if selectedChannel!.tag == 3 {
            setUpTopBarForPrivateChatLabels()
        } else {
            setUpTopBarForOtherChatLabels()
        }
        loadMessagesForSelectedChannel()
    }
}

func setUpTopBarIcons() {
    topVideoButton.titleLabel?.font = UIFont.fontAwesomeOfSize(17)
    topVoiceButton.titleLabel?.font = UIFont.fontAwesomeOfSize(17)
    topVideoButton.titleLabel?.text = String.fontAwesomeIconWithName(FontAwesome.VideoCamera)
    topVoiceButton.titleLabel?.text = String.fontAwesomeIconWithName(FontAwesome.VolumeUp)
}

func setUpTopBarForPrivateChatLabels() {
    let user: User!
    if selectedChannel?.users[0].userID == CurrentAccount.user?.userID {
        //set user to other user
        user = selectedChannel?.users[1]
    } else {
        user = selectedChannel?.users[0]
    }
    topNameLabel.text = "\(user.firstName!) \(user.lastName!)"
    topJobLabel.text = "Medical Marijuana Treatment Specialist"
    topOfficeLabel.text = "420 Evaluations - San Jose"
    topBarOtherChat.hidden = true
    topBarPrivateChat.hidden = false
}

func setUpTopBarForOtherChatLabels() {
    topChannelNameLabel.text = "\(selectedChannel!.name)"
    topNumberPeopleLabel.text = "\(selectedChannel!.users.count)"
    topTypeChannelIconLabel.font = UIFont.fontAwesomeOfSize(30)
    topTypeChannelIconLabel.text = String.fontAwesomeIconWithName(FontAwesome.Users)
    if selectedChannel?.tag == 1 {
        //Public Channel
        topTypeChannelLabel.text = "Public Chat"
    } else {
        //Group Channel
        topTypeChannelLabel.text = "Group Chat"
    }
    topBarOtherChat.hidden = false
    topBarPrivateChat.hidden = true
}

func sendParseChatMessageObject(message: ChatMessage) {
    selectedChannel!.sendMessage(message)
}

func getAllParseChannels() {
    let query: PFQuery = PFQuery(className: "TestChannels")
    query.findObjectsInBackgroundWithBlock { (objects: [AnyObject]?, error: NSError?) -> Void in
        if let error = error {
            // There was an error
            print("error getting parse channels")
        } else {
            //all the channels are here
            if let channels: [PFObject] = objects as? [PFObject]
            {
                for channel in channels {
                    self.channelList.append(Channel(obj: channel))
                }
                self.channelsTableView.reloadData()
                self.loadFirstParseChannel()
                self.startTimers()
            }
        }
    }
}

func loadMessagesForSelectedChannel() {
    chatMessages = selectedChannel!.messages
    dispatch_async(dispatch_get_main_queue()) {
        self.tableView.reloadData()
    }

    //self.tableView.reloadData()
    //self.tableView.layoutIfNeeded()
    //print("\n\n\n\(tableView.numberOfRowsInSection(0))\n\n\n")
    //self.tableView.scrollToRowAtIndexPath(NSIndexPath(forRow: (self.chatMessages.count - 1), inSection: 0), atScrollPosition: UITableViewScrollPosition.Bottom, animated: true)
    //print("done")
}

func startTimers() {
    selectedChannelTimer = NSTimer(timeInterval: 3.0, target: self, selector: "checkAndUpdateMessagesInSelectedChannel", userInfo: nil, repeats: true)
    NSRunLoop.currentRunLoop().addTimer(selectedChannelTimer, forMode: NSRunLoopCommonModes)
    //allChannelsTimer = NSTimer(timeInterval: 10.0, target: self, selector: "checkAndUpdateMessagesInAllChannels", userInfo: nil, repeats: true)
    //NSRunLoop.currentRunLoop().addTimer(allChannelsTimer, forMode: NSRunLoopCommonModes)
}

//Check every 1-3 seconds
func checkAndUpdateMessagesInSelectedChannel() {
    print("HERE BITCHES")
    let query: PFQuery = PFQuery(className: "TestMessage")
    query.whereKey("channel_id", equalTo: selectedChannel!.channelID)
    query.findObjectsInBackgroundWithBlock { (objects: [AnyObject]?, error: NSError?) -> Void in
        if let error = error {
            // There was an error
            print("error getting parse messages")
        } else {
            // objects has all the Posts the current user liked.
            if let messages: [PFObject] = objects as? [PFObject]
            {
                self.chatMessages.removeAll(keepCapacity: false)
                for message in messages {
                    self.chatMessages.append(ChatMessage(message: message["message_text"]! as! NSString as! String, dateSent: message.createdAt!, userSent: JSONParser.userFromUserID(JSONParser.getUsers()!, id: message["send_user_id"]! as! NSString as! String)!))
                }
                self.chatMessages.sort({$0.dateSent!.timeIntervalSinceNow < $1.dateSent!.timeIntervalSinceNow})

                self.tableView.reloadData()
            }
        }
    }
}

//Every 10 seconds call this
func checkAndUpdateMessagesInAllChannels() {
    //I need a dictionary that goes "channelID" -> Int(numberInArray)
    var dict = [String:Int]()
    var num = 0
    for channel in channelList {
        dict["\(channel.channelID)"] = num
        num += 1
    }
    //I should move the above code somewhere else, so it doesn't keep being coded
    let query: PFQuery = PFQuery(className: "TestMessage")
    query.findObjectsInBackgroundWithBlock { (objects: [AnyObject]?, error: NSError?) -> Void in
        if let error = error {
            // There was an error
            print("error getting parse messages")
        } else {
            // objects has all the Posts the current user liked.
            if let messages: [PFObject] = objects as? [PFObject]
            {
                //Clear messages for all channels
                for channel in self.channelList {
                    channel.messages.removeAll(keepCapacity: false)
                }
                for message in messages {
                    num = dict[message["channel_id"]! as! NSString as! String]!
                    self.channelList[num].messages.append(ChatMessage(message: message["message_text"]! as! NSString as! String, dateSent: message.createdAt!, userSent: CurrentAccount.user!))
                }
                self.chatMessages.sort({$0.dateSent!.timeIntervalSinceNow < $1.dateSent!.timeIntervalSinceNow})
                self.tableView.reloadData()
            }
        }
    }
    //Later find a way to see if a channel gained a new message
}

func getAllParseMessages() {
    let query: PFQuery = PFQuery(className: "TestMessage")
    query.findObjectsInBackgroundWithBlock { (objects: [AnyObject]?, error: NSError?) -> Void in
        if let error = error {
            // There was an error
            print("error getting parse messages")
        } else {
            // objects has all the Posts the current user liked.
            if let messages: [PFObject] = objects as? [PFObject]
            {
                for message in messages {
                    self.chatMessages.append(ChatMessage(message: message["message_text"]! as! NSString as! String, dateSent: message.createdAt!, userSent: CurrentAccount.user!))
                }
                self.chatMessages.sort({$0.dateSent!.timeIntervalSinceNow < $1.dateSent!.timeIntervalSinceNow})

                self.tableView.reloadData()
            }
        }
    }
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}


}

Answer 1

Update: I think my compiler thinks my second view uses the same view controller as the first, and as such all the IBOutlets are nil. I
think this because the method viewDidLoad is being called when I do
the segue.

No, it thinks that your second view controller uses "the same controller as the first" because your second view controller is defined by YOU as a subclass of ViewController . Therefore, it has all the same IBOutlets defined, but they are not connected.

When viewDidLoad is called function setUpTopBarIcons is triggered. topVideoButton gets accessed but because you have not connected it compiler debugger throws an error:

Unexpectedly found nil while unwrapping an optional value.

There are two ways out of this:

1. Connect all IBOutlets in your NewChannelPickerViewController
   (those which are defined by ViewController )
2. If you cannot accomplish (1) it means that you should define
   NewChannelPickerViewController as a subclass of UIViewController and not as a subclass of ViewController