How to implement UIPageViewController with a UIScrollView? - ios

Question

I took the Photo Scroller example from Apple's website and tried to implement my own Album by copying the code. Now, the UIScrollView is not visible. How do I make it appear?
The only code change that I made was in creating the UIPageViewController. In my case, it's a UIViewController that is opening it and not the AppDelegate.
#implementation BasePhotoViewController
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nil bundle:nibBundleOrNil];
if (self) {
// kick things off by making the first page
PhotoViewController *pageZero = [PhotoViewController photoViewControllerForPageIndex:0];
if (pageZero != nil)
{
// assign the first page to the pageViewController (our rootViewController)
//UIPageViewController *pageViewController = (UIPageViewController *) [[UIApplication sharedApplication] keyWindow].rootViewController;
UIPageViewController *pageViewController = [[UIPageViewController alloc] initWithTransitionStyle:0 navigationOrientation:0 options:nil];
//UIPageViewController *pageViewController = (UIPageViewController *)self.parentViewController;
pageViewController.dataSource = self;
[pageViewController setViewControllers:#[pageZero]
direction:UIPageViewControllerNavigationDirectionForward
animated:NO
completion:NULL];
}
}
return self;
}

Answer 1

You are not adding the pageViewController's view as a subview of BasePhotoViewController's view. Your BasePhotoViewController class should look something like this. Note the code in viewDidLoad.
BasePhotoViewController.h:
#interface BasePhotoViewController : UIViewController <UIPageViewControllerDataSource>
#property (nonatomic, strong) UIPageViewController * pageViewController;
#end
BasePhotoViewController.m:
#import "BasePhotoViewController.h"
#import "PhotoViewController.h"
#implementation BasePhotoViewController
#synthesize pageViewController;
- (id)initWithCoder:(NSCoder *)coder
{
self = [super initWithCoder:coder];
if (self) {
PhotoViewController *pageZero = [PhotoViewController photoViewControllerForPageIndex:0];
if (pageZero != nil)
{
self.pageViewController = [[UIPageViewController alloc] initWithTransitionStyle:0
navigationOrientation:0
options:nil];
self.pageViewController.dataSource = self;
[self.pageViewController setViewControllers:#[pageZero]
direction:UIPageViewControllerNavigationDirectionForward
animated:NO
completion:NULL];
}
}
return self;
}
- (void)viewDidLoad
{
[super viewDidLoad];
[self addChildViewController:self.pageViewController];
[self.view addSubview:self.pageViewController.view];
[self.pageViewController didMoveToParentViewController:self];
}
# pragma mark - UIPageViewControllerDataSource
- (UIViewController *)pageViewController:(UIPageViewController *)pvc viewControllerBeforeViewController:(PhotoViewController *)vc
{
NSUInteger index = vc.pageIndex;
return [PhotoViewController photoViewControllerForPageIndex:(index - 1)];
}
- (UIViewController *)pageViewController:(UIPageViewController *)pvc viewControllerAfterViewController:(PhotoViewController *)vc
{
NSUInteger index = vc.pageIndex;
return [PhotoViewController photoViewControllerForPageIndex:(index + 1)];
}
#end
Note: I've initialised the UIPageViewController in initWithCoder: because Apple's Photo Scroller code uses a storyboard. I removed the UIPageViewController from the storyboard and created a BasePhotoViewController in its place. If you are not loading BasePhotoViewController from a storyboard, you should move the code in initWithCoder: to the appropriate initialiser.
EDIT: See this sample project on github.