CODEWITHSUNDEEP
iosswift
Georgi Koemdzhiev
Georgi Koemdzhiev

Reputation: 11931

found nil while unwrapping optional

I am trying to create a simple application that consists of one Navigation controller with 2 screens controlled by a single UIViewController class. The app will allow the user to enter a number from 0 to 10 in a text field and when the user presses a button they will be taken to the 2nd screen showing if they guessed the randomly generated number. I get the "unexpectedly found nil while unwrapping an Optional value" error when I am accessing the text property of the label in the second screen. I dont uderstand why, I have connected the label with the class. Any suggetions?

This is my UI: enter image description here

This is my Navigation controller class code:

class MyNavController: UINavigationController {
var ranNum:Int = 0

override func viewDidLoad() {
    super.viewDidLoad()

    ranNum = (Int)(arc4random_uniform(10))

    NSLog("random number: \(ranNum)")
}

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

}

This is my Generic View controller class:

class GenericViewController: UIViewController {
@IBOutlet weak var inputTextField: UITextField!
@IBOutlet weak var outputLabel: UILabel!

var setThisLabel: String = "You Win!"

@IBAction func guessTheNumber(sender: AnyObject) {
    var generatedRanNumber = (parentViewController as! MyNavController).ranNum
    var userGuessNumer = inputTextField.text.toInt()

    if generatedRanNumber == userGuessNumer {
        outputLabel.text = "You Win!"
    } else if generatedRanNumber < userGuessNumer {
        outputLabel.text = "Think Less..."
    } else {
        outputLabel.text = "Think Big..."
    }
}
override func viewDidLoad() {
    super.viewDidLoad()

}

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

}

Upvotes: 0

Views: 66

Answers (2)

beyowulf
beyowulf

Reputation: 15321

Actually the problem is you are pushing from one instance of Generic View Controller to another without passing on the data. It is generally not recommended to use a generic subclass of UIViewController in this way. If you want your code to work as is, place the UILabel in the same view as your other UI and don't segue (i.e. only have one instance of GenericViewController). Or create two subclasses of UIViewController one called "GuessViewController" and the other called "AnswerViewController" and pass the guess value between them in prepareForSegue. GuessViewController would handle getting the string from the user and evaluate it. AnswerViewController would whether it's right or wrong. It is also generally not necessary to subclass UINavigationController. You could place that code in the viewDidLoad of GuessViewController.

Upvotes: 1

Andr&#233; Slotta
Andr&#233; Slotta

Reputation: 14030

change from

var generatedRanNumber = (parentViewController as! MyNavController).ranNum

to

var generatedRanNumber = (navigationController as! MyNavController).ranNum

also notice that arc4random_uniform(10) returns a number between 0 and 9. you tell the user to guess a number between 0 and 10.

Upvotes: 2

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