Handling ViewController in SwipeView with Three ViewController - ios

Question

I am following this link CustomPageControlForPageViewController to implement SwipeView menu. In this project, there are only two ViewControllers which involves in the swipe transition. But my requirement is of three ViewControllers like. So I am not getting any idea that, how to implement the UIPageViewController delegate methods with three ViewControllers which ll handle the transition from one view to other. Here is the code from the given link for two ViewControllers.
swipe.h
#interface RootViewController : UIViewController <UIPageViewControllerDataSource, UIPageViewControllerDelegate>
#property (strong, nonatomic) UIPageViewController *pageViewController;
#property (strong, nonatomic) UIView *pageControlCustomView;
#end
swipe.m
#interface RootViewController () {
NSArray *viewControllers;
UIView *selectionBar;
int SELECTOR_WIDTH;
int SELECTOR_Y;
UIButton *leftButton;
UIButton *rightButton;
moveSelectorBarLeftBlockType moveSelectorBarLeft;
moveSelectorBarRightBlockType moveSelectorBarRight;
UIViewController *firstVC;
UIViewController *secondVC;
}
#end
#implementation RootViewController
- (void)viewDidLoad {
[super viewDidLoad];
SELECTOR_WIDTH = self.view.frame.size.width/2;
SELECTOR_Y = self.navigationController.navigationBar.frame.size.height + Y_OFFSET_BELOW_NAVBAR + HEIGHT;
UIPageControl *pageControl = [UIPageControl appearance];
pageControl.pageIndicatorTintColor = [UIColor blackColor];
// Create page view controller
self.pageViewController = [[UIPageViewController alloc] initWithTransitionStyle:UIPageViewControllerTransitionStyleScroll navigationOrientation:UIPageViewControllerNavigationOrientationHorizontal options:nil];
self.pageViewController.dataSource = self;
self.pageViewController.delegate = self;
firstVC = [self.storyboard instantiateViewControllerWithIdentifier:#"firstViewController"];
secondVC = [self.storyboard instantiateViewControllerWithIdentifier:#"secondViewController"];
viewControllers = #[firstVC];
[self.pageViewController setViewControllers:viewControllers direction:UIPageViewControllerNavigationDirectionForward animated:NO completion:nil];
}
#pragma mark - Page View Controller Data Source
- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerBeforeViewController:(UIViewController *)viewController
{
if (self.pageViewController.viewControllers[0] == secondVC)
return firstVC;
return nil;
}
- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerAfterViewController:(UIViewController *)viewController
{
if (self.pageViewController.viewControllers[0] == firstVC)
return secondVC;
return nil;
}
- (void)pageViewController:(UIPageViewController *)pageViewController didFinishAnimating:(BOOL)finished previousViewControllers:(NSArray *)previousViewControllers transitionCompleted:(BOOL)completed {
if (completed) {
if (previousViewControllers[0] == secondVC) {
moveSelectorBarLeft();
}
else {
moveSelectorBarRight();
}
}
}

Answer 1

I recommend you to use your own array to store the order of your viewControllers.
Here is how I work with this delegate
- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerBeforeViewController:(UIViewController *)viewController {
NSUInteger index = [self.viewControllers indexOfObject:viewController];
if (index == 0) { return nil;}
index--;
UIViewController *targetViewController = [self.viewControllers objectAtIndex:index];
return targetViewController;
}
- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerAfterViewController:(UIViewController *)viewController {
NSUInteger index = [self.viewControllers indexOfObject:viewController];
index++;
if (index >= self.viewControllers.count) { return nil;}
UIViewController *targetViewController = [self.viewControllers objectAtIndex:index];
return targetViewController;
}