Index out of range (Can't get in the if condition)

Question

I am making a vocab app. User will be asked to choose a date, And after tapping one of date, prepareForSegue() will pass an array that contains about 30 vocabs, to ViewController. Then this viewController begin to display a vocab label, after one second, It display a Image, and after one more second it will diplay meaning of vocab.

This is my code.

class ViewController: UIViewController {

@IBOutlet weak var vocabImage: UIImageView!
@IBOutlet weak var meaningLabel: UILabel!
@IBOutlet weak var vocabLabel: UILabel!

var vocabData = [String]()
var meaningData = [String]()

var vocabNumber : Int = 0
var sceneNumber : Int = 0

var speed : Double = 0.01

var commentSwitch = false



var audioPlayer = AVAudioPlayer()



override func viewDidLoad() {
    super.viewDidLoad()

    controlTower()
        }

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


func controlTower()  {
    switch sceneNumber {
    case 0:

        if vocabNumber == 0 && commentSwitch == false{
            let myAlert = UIAlertController(title: "Lets start to memorize it,머리 속에 단어를 입력하는 단계", message: "뜻을 예측해 보자구요", preferredStyle: UIAlertControllerStyle.Alert)
            let myAlertAction = UIAlertAction(title: "Start", style: UIAlertActionStyle.Default, handler: { Void in
                self.commentSwitch = true
                self.controlTower()
            })
            myAlert.addAction(myAlertAction)
            presentViewController(myAlert, animated: true, completion:nil)

        }else{

        displayVocab()

        NSTimer.scheduledTimerWithTimeInterval(speed, target: self, selector: #selector(ViewController.controlTower), userInfo: nil, repeats: false)
        print("\(vocabNumber) - 0")
        sceneNumber = 1

        }
    case 1:
        displayImage()

        NSTimer.scheduledTimerWithTimeInterval(speed, target: self, selector: #selector(ViewController.controlTower), userInfo: nil, repeats: false)
        print("\(vocabNumber) - 1")
        sceneNumber = 2

    case 2:
        displayMeaning()

        NSTimer.scheduledTimerWithTimeInterval(speed, target: self, selector: #selector(ViewController.controlTower), userInfo: nil, repeats: false)
        print("\(vocabNumber) - 2")
        sceneNumber = 3


    case 3:
        if (vocabNumber  == vocabData.count ){

            deleteAll()
            sceneNumber = 0
            vocabNumber = 0
            print("I can't get in here")

        }else {




        deleteAll()
        sceneNumber = 0



        NSTimer.scheduledTimerWithTimeInterval(speed, target: self, selector: #selector(ViewController.controlTower), userInfo: nil, repeats: false)
            print("\(vocabNumber) - 3")

            controlTower()
            vocabNumber++


        }
    default: break

    }
}

func displayVocab() {
    //sound
    read()
    vocabLabel.text = vocabData[vocabNumber]

func displayImage() {
    vocabImage.image = UIImage(named: vocabData[vocabNumber])

func displayMeaning(){

    meaningLabel.text = meaningData[vocabNumber]
    }
}

So each time before diplay something, it will visit controlTower, keep showing data, until it reaches condition (vocabNumber == vocabData.count) && (scenenumber == 3).

Here is my problem. when vocabNumber become 31 (total data.count = 31) it would get

fatal error: Index out of range

at the func displayVocab() {

    vocabLabel.text = vocabData[vocabNumber]
}

here(I think vocabNumber)

I can't figure out why it doesn't work.

Even I put

if (vocabNumber <= vocabData.count){

in the function, this still can't get the case 3 (if condition)

Let me know which part of code is wrong for this error.

Thank you.

score 0 · Accepted Answer · answered Apr 10 '16 at 09:15

vocabData.count goes as number of elements, but elements go from 0 to count - 1. So you have to check vocabData.count -1.

so, in this condition:

(vocabNumber == vocabData.count) && (scenenumber == 3)

Go for:

(vocabNumber == vocabData.count - 1) && (scenenumber == 3)

Index out of range (Can't get in the if condition)

1 Answers1