在swift解开Optional值时意外发现nil

Question

I tried this code

  let secondView = SecondViewController(nibName: "secondView", bundle: nil)
    secondView.secondViewLabel.text = self.TextBox.text
    navigationController?.pushViewController(secondView, animated: true)

I am trying to pass the value from the text box to a label in the next view controller.But i get an error

I also tried copying the text box value to a sting declared in the second View controller that also returns nil.

let secondView = SecondViewController(nibName: "secondView", bundle: nil)
    secondView.toPass = self.TextBox.text
    navigationController?.pushViewController(secondView, animated: true)
    println(secondView.toPass) // i get the string printed here

in second view controller

      var toPass:String! 

in view did load

    secondLabel.text = toPass
     println(toPass) // i get the string printed nil

help me guys i am new to swift

Answer 1

Make the type of toPass a String conditional like so

var toPass: String?

In viewDidLoad, do this :

if let passedString = toPass {
    secondLabel.text = toPass
    println(toPass)
}

Then put a breakpoint inside the if let block to see if toPass ever had a value or it isn't being set at all. Really need to know what type the TextBox is.

[Edit 2]

If the problem is that the value is being set before the viewController secondView has been decoded from a nib, I'd suggest you make a convenience initializer that uses the initWithNib but also takes the extra title string or whatever it is. There you can set the value of your textLabel's text to the parameter the new initializer takes. Of course this would mean that you'll have to subclass UIViewController.