ISO: Images not showing up in a page view controller app - ios

Question

I am new to iOS development, and I am having some issues showing images in a simple page view controller photo gallery.
The problem I am having is that the images in the child view won't be displayed. The only thing showing is a blank page.
Here is the view controller file holding page view controller:
#import "RTPGalleryViewController.h"
#import "RTPSinglePhotoViewController.h"
#import "JMImageCache.h"
#interface RTPGalleryViewController ()
#end
#implementation RTPGalleryViewController
#synthesize photosArray, pageViewController, pagesArray;
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Custom initialization
}
return self;
}
- (void)viewDidLoad
{
[super viewDidLoad];
pagesArray = [[NSMutableArray alloc] init];
[self generatePhotoViews];
self.pageViewController = [[UIPageViewController alloc] initWithTransitionStyle:UIPageViewControllerTransitionStyleScroll navigationOrientation:UIPageViewControllerNavigationOrientationHorizontal options:nil];
self.pageViewController.dataSource = self;
[[self.pageViewController view] setFrame:[[self view] bounds]];
RTPSinglePhotoViewController *initialViewController = [pagesArray objectAtIndex:0];
NSArray *viewControllers = [NSArray arrayWithObject:initialViewController];
[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 - 30);
[self addChildViewController:self.pageViewController];
[[self view] addSubview:[self.pageViewController view]];
[self.pageViewController didMoveToParentViewController:self];
// Do any additional setup after loading the view.
}
-(void) initWithPhotoArray:(NSMutableArray *) photos{
self.photosArray = photos;
}
-(void) generatePhotoViews{
for (int i=0; i< [photosArray count]; i++) {
RTPSinglePhotoViewController *view = [[RTPSinglePhotoViewController alloc] init] ;
view.imageUrl = [photosArray objectAtIndex:i];
view.pageIndex = i;
[pagesArray addObject:view];
}
}
- (RTPSinglePhotoViewController *)viewControllerAtIndex:(NSUInteger)index
{
NSLog(#"PHOTO ARRAY COUNT IS: %lu", (unsigned long)[photosArray count]);
if ([self.pagesArray count] == 0) {
return nil;
}
return [pagesArray objectAtIndex:index];
;
}
#pragma mark - Page View Controller Data Source
- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerBeforeViewController:(UIViewController *)viewController
{
NSUInteger index = ((RTPSinglePhotoViewController*) viewController).pageIndex;
if ((index == 0) || (index == NSNotFound)) {
return nil;
}
NSLog(#"THE INDEX NOW IS %lu",(unsigned long)index);
index--;
return [self viewControllerAtIndex:index];
}
- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerAfterViewController:(UIViewController *)viewController
{
NSUInteger index = ((RTPSinglePhotoViewController*) viewController).pageIndex;
if (index == ([pagesArray count]-1) || index == NSNotFound) {
return nil;
}
NSLog(#"THE INDEX NOW IS %lu",(unsigned long)index);
index++;
return [self viewControllerAtIndex:index];
}
- (NSInteger)presentationCountForPageViewController:(UIPageViewController *)pageViewController
{
return [self.photosArray count];
}
- (NSInteger)presentationIndexForPageViewController:(UIPageViewController *)pageViewController
{
return 0;
}
#end
RTPSinglePhotoViewController is the content view controller holding images here is the code:
#import "RTPSinglePhotoViewController.h"
#import "JMImageCache.h"
#interface RTPSinglePhotoViewController ()
#end
#implementation RTPSinglePhotoViewController
#synthesize imageView,imageUrl;
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Custom initialization
}
return self;
}
- (void)viewDidLoad
{
[super viewDidLoad];
NSString * path = imageUrl;
NSURL * url = [NSURL URLWithString:path];
// [cell.thumbnailImageView setImageWithURL:url key:nil placeholder:nil completionBlock:nil failureBlock:nil];
[[JMImageCache sharedCache] imageForURL:url completionBlock:^(UIImage *downloadedImage) {
imageView.image = downloadedImage;
} failureBlock:nil];
// Do any additional setup after loading the view.
}
#end
Now, according to the log, the image is being downloaded/cached properly, it is just not showing up. Seeing a blank page instead of photo. What am I doing wrong?
Any suggestions would be appreciated!

Answer 1

I suppose you are not using storyboard.
The way you are allocating view controllers is:
RTPSinglePhotoViewController *view = [[RTPSinglePhotoViewController alloc] init] ;
Where it should be:
RTPSinglePhotoViewController *view = [[RTPSinglePhotoViewController alloc] initWithNibName:#"The name of the xib associated with this controller" bundle: [NSBundle mainBundle]];
The problem is that you are not associating any view to your view controller, therefore nothing is displayed
EDIT: Since you're using storyboards the right way to instantiate the view controller is:
RTPSinglePhotoViewController *view = (RTPSinglePhotoViewController *)[self.storyboard instantiateViewControllerWithIdentifier:#"your_controllers_storyboard_id"];