Unexpectly found nil

Question

I'm doing updating for CoreData and I need to load data for editing to textfields. and in AddViewController in viewDidLoad I have

if let myData = data {

            knihaTextField.text = data.valueForKey("kniha") as? String
            autorTextField.text = data.valueForKey("autor") as? String
            rokTextField.text = data.valueForKey("rok") as? String
            vydavatelstvoTextField.text = data.valueForKey("vydavatelstvo") as? String
            stranyTextField.text = data.valueForKey("strany") as? String

        }

In knihaTextField.text = data.valueForKey("kniha") as? String I'm getting error

fatal error: unexpectedly found nil while unwrapping an Optional value

full code :

http://pastebin.com/yF53nbSE

I'm doing segue from DetailView to PridatView - full code:

http://pastebin.com/BeG4eZHX

Answer 1

Guys anyway thanks for you help. But I solved it with friend. And decided that it's need to be in viewDidAppear

 override public func viewDidAppear(animated: Bool) {
        if let myData = data {
            knihaTextField.text = myData.valueForKey("kniha") as? String
            autorTextField.text = myData.valueForKey("autor") as? String
            rokTextField.text = myData.valueForKey("rok") as? String
            vydavatelstvoTextField.text = myData.valueForKey("vydavatelstvo") as? String
            stranyTextField.text = myData.valueForKey("strany") as? String
        } 
    }