swift - fatal error - 解包可选值时意外发现 nil

Question

我正在尝试使用 swift 开发聊天应用程序，当我在运行期间构建并运行该项目时，当我尝试转到 ChatVewController 时，它显示此 EXC 错误指令错误。

控制台显示

fatal error :解包可选值时意外发现 nil。

这是我的代码。

import UIKit
import Firebase

class SportsLogin: UIViewController {

// MARK: Properties
let ref: Firebase  = Firebase(url: BASE_URL2)


override func viewDidLoad() {
    super.viewDidLoad()
}

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

    let navVC2 = segue.destinationViewController as! UINavigationController
    let chatVC2 = navVC2.viewControllers.first as! SportsViewController

    chatVC2.senderId = ref.authData.uid // Assign the local user’s ID to chatVc.senderId; this is the local ID that JSQMessagesViewController uses to coordinate messages.
    chatVC2.senderDisplayName = "" // chatVc.senderDisplayName is set to empty string, since this is an anonymous chat room.
}



@IBAction func loginDidTouch(sender: AnyObject) {

    ref.authAnonymouslyWithCompletionBlock { (error, authData) -> Void in
        if error != nil {  // Check for an authentication error.
            print(error.description)
            return
        }
        // Inside of the closure, trigger the segue to move to ChatViewController.
        print(self.ref.authData)
        self.performSegueWithIdentifier("SportChat", sender: self)
    }

}

}

有错误的行是

chatVC2.senderId = ref.authData.uid // Assign the local user’s ID to chatVc.senderId; this is the local ID that JSQMessagesViewController uses to coordinate messages.

谢谢!

Answer 1

SportsViewController 是什么？如果SportViewController是自己delcare的话，变量成员应该是sendId，是class memeber，NSString类型。