Xcode won't open up ContentViewController but stays on the launch screen - ios

Question

I am trying to compile my Xcode application. It builds successfully however it doesn't get past the launch screen.
Also It keeps referring me to this particular line of code: instantiateViewControllerWithIdentifier (full code below) and in the logs I get this message:
Unknown class ContentViewController in Interface Builder file.
Could not cast value of type 'UIViewController' (0x10741f418) to 'HelloHi.ContentViewController' (0x1049aa2e0).
(lldb)
Can anyone please help me fix this?
import UIKit
class ViewController: UIViewController, UIPageViewControllerDataSource {
var pageViewController: UIPageViewController!
var pageTitles: NSArray!
var pageImages: NSArray!
override func viewDidLoad() {
super.viewDidLoad()
self.pageTitles = NSArray(objects: "Welcome", "Hello")
self.pageImages = NSArray(objects: "page1", "page2")
self.pageViewController = self.storyboard?.instantiateViewControllerWithIdentifier("PageViewController") as! UIPageViewController
self.pageViewController.dataSource = self
var startVC = self.viewControllerAtIndex(0) as ContentViewController
var viewControllers = [startVC]
self.pageViewController.setViewControllers(viewControllers, direction: .Forward, animated: true, completion: nil)
self.pageViewController.view.frame = CGRectMake(0, 30, self.view.frame.width, self.view.frame.size.height - 60 )
self.addChildViewController(self.pageViewController)
self.view.addSubview(self.pageViewController.view)
self.pageViewController.didMoveToParentViewController(self)
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
#IBAction func restartAction(sender: AnyObject) {
var startVC = self.viewControllerAtIndex(0) as ContentViewController
var viewControllers = [startVC]
self.pageViewController.setViewControllers(viewControllers, direction: .Forward, animated: true, completion: nil)
}
func viewControllerAtIndex(index: Int) -> ContentViewController
{
if ((self.pageTitles.count == 0) || (index >= self.pageTitles.count))
{
return ContentViewController()
}
var vc: ContentViewController = self.storyboard?.instantiateViewControllerWithIdentifier("ContentViewController") as! ContentViewController
vc.imageFile = self.pageImages[index] as! String
vc.titleText = self.pageTitles[index] as! String
vc.pageIndex = index
return vc
}
//MARK: - Page View Controller Data Source
func pageViewController(pageViewController: UIPageViewController, viewControllerBeforeViewController viewController: UIViewController) -> UIViewController? {
var vc = viewController as! ContentViewController
var index = vc.pageIndex as Int
if (index == 0 || index == NSNotFound)
{
return nil
}
index--
return self.viewControllerAtIndex(index)
}
func pageViewController(pageViewController: UIPageViewController, viewControllerAfterViewController viewController: UIViewController) -> UIViewController? {
var vc = viewController as! ContentViewController
var index = vc.pageIndex as Int
if (index == NSNotFound)
{
return nil
}
index++
if (index == self.pageTitles.count)
{
return nil
}
return self.viewControllerAtIndex(index)
}
func presentationCountForPageViewController(pageViewController: UIPageViewController) -> Int {
return self.pageTitles.count
}
func presentationIndexForPageViewController(pageViewController: UIPageViewController) -> Int {
return 0
}
}

Answer 1

The error message indicates that the view controller in the Interface Builder file has the wrong class set. Select the offending controller, open the identity inspector and change the class name to the correct UIViewController subclass. Presumably this is ContentViewController for you.
Of course, you need to define the the ContentViewController class somewhere in the project. It is not in the code you posted, and following the error message, it is not anywhere else in your project.