UIPageViewController loads wrong page - ios

Question

I am doing a tutorial in my iOS app. But I have a bug in my PageViewController.
My tutorial has 5 pages. But the second movement that I do to change page always appears the previous page repeatedly.
For example, appears page0, move to page1, and then when i want to appear page2, appears page1 again.
This occurs to both sides.
This is my code:
- (void)viewDidLoad {
[super viewDidLoad];
self.pageTexts = #[#"",intro1, intro2, intro3, intro4];
self.index = 0;
self.viewControllerPageContentOne = [[ViewControllerPageContentOne alloc] init];
self.viewControllerPageContentTwo = [[ViewControllerPageContentTwo alloc] init];
self.viewControllerPageContentThree = [[ViewControllerPageContentThree alloc] init];
self.pageViewController = [self.storyboard instantiateViewControllerWithIdentifier:#"PageViewController"];
self.pageViewController.dataSource = self;
UIViewController* first = [self viewControllerUsed];
NSArray *viewControllers = [NSArray arrayWithObject:first];
[self.pageViewController setViewControllers:viewControllers direction:UIPageViewControllerNavigationDirectionForward animated:NO completion:nil];
[self addChildViewController:self.pageViewController];
[self.view addSubview:self.pageViewController.view];
[self.pageViewController didMoveToParentViewController:self];
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
}
- (UIViewController *)viewControllerUsed{
if (self.index == 0) {
self.viewControllerPageContentOne=[self.storyboard instantiateViewControllerWithIdentifier:#"ViewControllerPageContentOne"];
return self.viewControllerPageContentOne;
}
else if (self.index == 1)
{
self.viewControllerPageContentTwo=[self.storyboard instantiateViewControllerWithIdentifier:#"ViewControllerPageContentTwo"];
self.viewControllerPageContentTwo.titleText = self.pageTexts[self.index];
return self.viewControllerPageContentTwo;
}
else if (self.index == 2)
{
self.viewControllerPageContentTwo=[self.storyboard instantiateViewControllerWithIdentifier:#"ViewControllerPageContentTwo"];
self.viewControllerPageContentTwo.titleText = self.pageTexts[self.index];
return self.viewControllerPageContentTwo;
}
else if (self.index == 3)
{
self.viewControllerPageContentTwo=[self.storyboard instantiateViewControllerWithIdentifier:#"ViewControllerPageContentTwo"];
self.viewControllerPageContentTwo.titleText = self.pageTexts[self.index];
return self.viewControllerPageContentTwo;
}
else if (self.index == 4)
{
self.viewControllerPageContentThree=[self.storyboard instantiateViewControllerWithIdentifier:#"ViewControllerPageContentThree"];
self.viewControllerPageContentThree.titleText = self.pageTexts[self.index];
return self.viewControllerPageContentThree;
}
else{
return nil;
}
}
#pragma mark - Page View Controller Data Source
- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerBeforeViewController:(UIViewController *)viewController {
self.index--;
if (self.index < 0) {
self.index = [self.pageTexts count]-1;
}
return [self viewControllerUsed];
}
- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerAfterViewController:(UIViewController *)viewController {
self.index++;
if (self.index > [self.pageTexts count]-1) {
self.index = 0;
}
return [self viewControllerUsed];
}
- (NSInteger)presentationCountForPageViewController:(UIPageViewController *)pageViewController
{
return [self.pageTexts count];
}
- (NSInteger)presentationIndexForPageViewController:(UIPageViewController *)pageViewController
{
return 0;
}
I suppose that there is an error in index pages but I don’t know it.
Thanks

Answer 1

I think your problem is that you are creating class level properties for view controllers. And that too you are initialising them in viewDidLoad
self.viewControllerPageContentOne = [[ViewControllerPageContentOne alloc] init];
self.viewControllerPageContentTwo = [[ViewControllerPageContentTwo alloc] init];
self.viewControllerPageContentThree = [[ViewControllerPageContentThree alloc] init];
My advise is to create view controllers and save them in an array like this:
UIViewController *page0 = [self.storyboard instantiateViewControllerWithIdentifier:#"ViewControllerPageContentOne"];
UIViewController *page1 = [self.storyboard instantiateViewControllerWithIdentifier:#"ViewControllerPageContentTwo"]
page3.titleText = self.pageTexts[1];
UIViewController *page2 = [self.storyboard instantiateViewControllerWithIdentifier:#"ViewControllerPageContentTwo"]
page3.titleText = self.pageTexts[2];
UIViewController *page3 = [self.storyboard instantiateViewControllerWithIdentifier:#"ViewControllerPageContentTwo"]
page3.titleText = self.pageTexts[3];
UIViewController *page4 = [self.storyboard instantiateViewControllerWithIdentifier:#"ViewControllerPageContentThree"];
[self.viewControllers addObject:page0];
[self.viewControllers addObject:page1];
[self.viewControllers addObject:page2];
[self.viewControllers addObject:page3];
[self.viewControllers addObject:page4];
And then in your viewControllerUsed simply return viewControllers from self.viewControllers like self.viewControllers[self.index].