Not the same as: Passing values ... and Swift - programmatically ... was not helpful for my situation.
When I press a button in one file (NSViewController)
@IBAction func bookPressed(sender: NSButton) { 
    var popVC = NSStoryboard(name: "Main", 
        bundle: nil)?.instantiateControllerWithIdentifier("PopoverViewController") as? NSViewController
    popVC.bookName = "hello"
}
I want this file to show the results of bookName = "hello"
class PopoverViewController: NSViewController {
    let bookName: String = ""
    override func viewDidLoad() {
        super.viewDidLoad()
        println(bookName)
    }
}
What am I missing?
 
     
    