gistfile1.txt

// 1. set up the intial view with the first Feed Item

- (void) initFeedsPageViewController {
    
    ...
    
    FeedItem * firstFeedItem = self.feedItemsArray[0];
    PSHCoverFeedPageViewController * currentPagePageViewController = [[PSHCoverFeedPageViewController alloc] init];
    currentPagePageViewController.feedType = firstFeedItem.type;
    currentPagePageViewController.messageLabelString = firstFeedItem.message;
    currentPagePageViewController.infoLabelString = [NSString stringWithFormat:@"%@ - %@", [self.dateFormatter stringFromDate:firstFeedItem.updatedTime], firstFeedItem.source.name];
    currentPagePageViewController.likesCount = [firstFeedItem.likesCount integerValue];
    currentPagePageViewController.commentsCount = [firstFeedItem.commentsCount integerValue];
    currentPagePageViewController.feedItemGraphID = firstFeedItem.graphID;
    currentPagePageViewController.feedType = firstFeedItem.type;
    currentPagePageViewController.likedByMe = firstFeedItem.likedByMe.boolValue;
    
    [self.feedsPageViewController setViewControllers:@[currentPagePageViewController] direction:UIPageViewControllerNavigationDirectionForward animated:YES completion:^(BOOL finished) {
    }];
    ...

// 2. set up view controller for previous page

#pragma mark - UIPageViewController dataSource

- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerBeforeViewController:(UIViewController *)viewController {
    
    PSHCoverFeedPageViewController *currentViewController = (PSHCoverFeedPageViewController*) viewController;
    NSInteger currentIndex = currentViewController.currentIndex;
    
    // prev page
    if (currentIndex == 0){
        return nil;
    }else{
        NSInteger previousIndex = currentIndex - 1;
        FeedItem * previousFeedItem = self.feedItemsArray[previousIndex];
        PSHCoverFeedPageViewController * prevPageViewController = [[PSHCoverFeedPageViewController alloc] init];
        prevPageViewController.feedType = previousFeedItem.type;
        prevPageViewController.messageLabelString = previousFeedItem.message;
        prevPageViewController.infoLabelString = [NSString stringWithFormat:@"%@ - %@", [self.dateFormatter stringFromDate:
        ....
    }
    return prevPageViewController;
}

// 3. set up  view controller for next page

- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerAfterViewController:(UIViewController *)viewController {
    
    PSHCoverFeedPageViewController *currentViewController = (PSHCoverFeedPageViewController*) viewController;
    NSInteger currentIndex = currentViewController.currentIndex;
    NSInteger nextIndex = currentIndex+1;
    
    if (currentIndex < [self.feedItemsArray count]-1){
        
        FeedItem * nextFeedItem = self.feedItemsArray[nextIndex];
        
        PSHCoverFeedPageViewController * nextPageViewController = [[PSHCoverFeedPageViewController alloc] init];
        nextPageViewController.feedType = nextFeedItem.type;
        nextPageViewController.messageLabelString = nextFeedItem.message;
        nextPageViewController.infoLabelString = [NSString stringWithFormat:@"%@ - %@", [self.dateFormatter stringFromDate:nextFeedItem.updatedTime], nextFeedItem.source.name];
        nextPageViewController.likesCount = [nextFeedItem.likesCount integerValue];
        ...
        return nextPageViewController;
    }
}