xcode - Swift exc_bad_instruction xcode

Question

我是iso编程的新手。我正在尝试在视图控制器上的应用程序中创建一个小测验。它有 1 个标签和 4 个按钮。我得到 EXC_BAD_INSTRUCTION了QLabel.text = Questions[QNumber].Question. 我删除了情节提要上的标签和按钮，然后将它们连接到 ViewCONtroller.swift，但我仍然收到错误消息。

它还说： QLabel = nil和Buttons = nil

编码：

import UIKit

struct Question {

var Question: String!
var Answers: [String]!
var Answer: Int!


}

class ViewController: UIViewController {

@IBOutlet weak var QLabel: UILabel!

@IBOutlet var Buttons: [UIButton]!

var Questions = [Question]()
var QNumber = Int()
override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.

    Questions = [Question(Question: "enter", Answers: ["aaa", "bbb", "ccc", "ddd"], Answer: 2)]

    PickQuestion()
}

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

func PickQuestion(){

    if Questions.count > 0{
        QNumber = 0
        QLabel.text = Questions[QNumber].Question

        for i in 0..<Buttons.count{

            Buttons[i].setTitle(Questions[QNumber].Answers[i], forState: UIControlState.Normal)

        }

        Questions.removeAtIndex(QNumber)
    }
    else{
        NSLog("Done!")
    }
}

}