Грешки на PageView Controller „Очакван селектор за Objective C“

Имам толкова много проблеми със създаването на контролер за изглед на страници. Направих корекции в кода си три пъти, но ПРОДЪЛЖАВАМ да получавам следната грешка: „Очакван селектор за метод Objective C“. Получавам и друго съобщение за грешка, което гласи Липсва „@end“. Може ли някой да ми каже защо получавам тези съобщения? :л

    #import "InstructionContentViewController.h"
    #import "StorageViewController.h"

    @interface StorageViewController ()

    @end

    @implementation StorageViewController

    - (void)viewDidLoad

    {
    [super viewDidLoad];
    // Create the data model
    _pageTitles = @[@"Over 200 Tips and Tricks", @"Discover Hidden Features", @"Bookmark     Favorite Tip", @"Free Regular Update"];
    _pageImages = @[@"instructions1.png", @"instructions2.png", @"instructions3.png", @"instructions4.png"];

    // Create page view controller
    self.instructionViewController = [self.storyboard instantiateViewControllerWithIdentifier:@"InstructionViewController"];
    self.instructionViewController.dataSource = self;

    InstructionContentViewController *startInstructViewController = [self viewControllerAtIndex:0];
    NSArray *viewControllers = @[startInstructViewController];
    [self.instructionViewController setViewControllers:viewControllers direction:UIPageViewControllerNavigationDirectionForward animated:NO completion:nil];

    // Change the size of page view controller
    self.instructionViewController.view.frame = CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height - 50);

    [self addChildViewController:_instructionViewController];
    [self.view addSubview:_instructionViewController.view];
    [self.instructionViewController didMoveToParentViewController:self];

     }

     - (void)didReceiveMemoryWarning
     {
      [super didReceiveMemoryWarning];
      // Dispose of any resources that can be recreated.
      }

     - (IBAction)startWalkthrough:(id)sender {

    InstructionContentViewController *startingInstructViewController = [self viewControllerAtIndex:0];
    NSArray *viewControllers = @[startingInstructViewController];
    [self.instructionViewController setViewControllers:viewControllers direction:UIPageViewControllerNavigationDirectionReverse animated:NO completion:nil];
}

#pragma mark - Page View Controller Data Source Methods:

- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerBeforeViewController:(UIViewController *)viewController
{
    NSUInteger index = ((InstructionContentViewController*) viewController).pageIndex;

    if ((index == 0) || (index == NSNotFound)) {
        return nil;
    }

      index--;
      return [self viewControllerAtIndex:index];
    }

      - (UIViewController *)pageViewController:(UIPageViewController *)pageViewController      viewControllerAfterViewController:(UIViewController *)viewController
    {
    NSUInteger index = ((InstructionContentViewController*) viewController).pageIndex;

    if (index == NSNotFound) {
        return nil;
    }

    index++;
    if (index == [self.pageTitles count]) {
        return nil;
    }
    return [self viewControllerAtIndex:index];
    }

     - (InstructionContentViewController *)viewControllerAtIndex:(NSUInteger)index
    {
    if (([self.pageTitles count] == 0) || (index >= [self.pageTitles count])) {
        return nil;
    }

    // Create a new view controller and pass suitable data.
    InstructionContentViewController *instructionContentViewController = [self.storyboard instantiateViewControllerWithIdentifier:@"InstructionContentViewController"];
    instructionContentViewController.instructimageFile = self.pageImages[index];
    instructionContentViewController.instructtitleText = self.pageTitles[index];
    instructionContentViewController.pageIndex = index;

    return instructionContentViewController;


    }


       - (NSInteger)presentationCountForPageViewController:(UIPageViewController     *)pageViewController
     {
    return [self.pageTitles count];
    }

    - (NSInteger)presentationIndexForPageViewController:(UIPageViewController *)pageViewController
{
    return 0;
}



     @end