UIPageViewController index is not working properly - ios

Question

Basically, I am making a page app, which use UIPageViewController. When the user scrolls the page, they can see different content. The problem now is, when I scroll the page, the first and second page works properly, and the index is correct. But when I scroll to the third page, the index keeps at "1", and don't change afterwards. And the other page keeps the appearance of the second page, whose index is "1".
I was following the tutorial: http://www.appcoda.com/uipageviewcontroller-storyboard-tutorial/
My code:
View Controller.h
#import <UIKit/UIKit.h>
#import "PageContentViewController.h"
#import "PageViewController.h"
#interface ViewController : UIViewController<UIPageViewControllerDataSource, UIPageViewControllerDelegate>
#property (strong, nonatomic) PageViewController *pageViewController;
#property (strong, nonatomic) NSArray *pageTitles;
#end
View Controller.m:
#import "ViewController.h"
#interface ViewController ()
#end
#implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
self.pageTitles = #[#"First Page", #"Second Page", #"Third Page"];
self.pageViewController = [self.storyboard instantiateViewControllerWithIdentifier:#"PageViewController"];
self.pageViewController.dataSource = self;
if ([self.pageTitles count])
{
PageContentViewController *startingViewController = [self viewControllerAtIndex: 0];
NSArray *viewControllers = #[startingViewController];
[self.pageViewController setViewControllers:viewControllers direction:UIPageViewControllerNavigationDirectionForward animated:NO completion:nil];
self.pageViewController.view.frame = CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height);
[self addChildViewController:self.pageViewController];
[self.view addSubview:self.pageViewController.view];
[self.pageViewController didMoveToParentViewController:self];
}
}
- (PageContentViewController *) viewControllerAtIndex: (NSUInteger)index{
if (index < [self.pageTitles count])
{
PageContentViewController *pageContentViewController = [self.storyboard instantiateViewControllerWithIdentifier:#"PageContentViewController"];
pageContentViewController.titleText = self.pageTitles[index];
NSLog(#"%li", index);
UIColor *backgroundColor;
switch (index) {
case 0:
backgroundColor = [UIColor greenColor];
break;
case 1:
backgroundColor = [UIColor blueColor];
break;
case 2:
backgroundColor = [UIColor purpleColor];
break;
default:
break;
}
pageContentViewController.backgroundColor = backgroundColor;
return pageContentViewController;
}
return nil;
}
- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerAfterViewController:(UIViewController *)viewController
{
NSUInteger index = ((PageContentViewController *)viewController).pageIndex;
if (index == NSNotFound)
{
return nil;
}
index++;
if (index == [self.pageTitles count])
{
return nil;
}
return [self viewControllerAtIndex:index];
}
- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerBeforeViewController:(UIViewController *)viewController
{
NSUInteger index = ((PageContentViewController *)viewController).pageIndex;
if (index == 0 || index == NSNotFound)
{
return nil;
}
index--;
return [self viewControllerAtIndex:index];
}
- (NSInteger) presentationCountForPageViewController:(UIPageViewController *)pageViewController
{
return [self.pageTitles count];
}
- (NSInteger) presentationIndexForPageViewController:(UIPageViewController *)pageViewController
{
return 0;
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
#end
Page Content View Controller.h
#import <UIKit/UIKit.h>
#interface PageContentViewController : UIViewController
#property (weak, nonatomic) IBOutlet UIView *backgroundView;
#property (weak, nonatomic) IBOutlet UILabel *titleLable;
#property (nonatomic) NSUInteger pageIndex;
#property (strong, nonatomic) NSString *titleText;
#property (strong, nonatomic) UIColor *backgroundColor;
#end
Page Content View Controller.m
#import "PageContentViewController.h"
#interface PageContentViewController ()
#end
#implementation PageContentViewController
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view.
self.titleLable.text = self.titleText;
[self.backgroundView setBackgroundColor:self.backgroundColor];
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
/*
#pragma mark - Navigation
// In a storyboard-based application, you will often want to do a little preparation before navigation
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
// Get the new view controller using [segue destinationViewController].
// Pass the selected object to the new view controller.
}
*/
#end

Answer 1

In viewControllerAtIndex:, you need to set the value of pageIndex property of the pageContentViewController:
pageContentViewController.pageIndex = index;