MWPhotoBrowser not showing the correct image when selected from a collection view

Question

In my app, there's only 2 views. First view is a collection view and when you tap on an image, it goes to the MWPhotoBrowser to view the image in it's full size.

I'm retrieving ~100 images over the internet and adding them to a NSMutableArray. There's a problem with this. When I run the app for the first time and select a thumbnail image from the grid it shows the last image. Not the one I selected. Note that I emphasized on the first time because it only happens in the first time. If I go back and tap on another image, it correctly shows the selected one. Below is a screenshot of how its supposed to work.

Here is the code

#import "UIImageView+WebCache.h"
#import "ViewController.h"
#import "MWPhotoBrowser.h"
#import "Image.h"
#import "ImageCell.h"

@interface ViewController () <UICollectionViewDelegate, UICollectionViewDataSource, MWPhotoBrowserDelegate>

@property (strong, nonatomic) NSMutableArray *images;
@property (strong, nonatomic) NSMutableArray *browserImages;
@property (strong, nonatomic) MWPhotoBrowser *browser;

@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];

    self.browser = [[MWPhotoBrowser alloc] initWithDelegate:self];
    self.browser.displayActionButton = YES;
    self.browser.displayNavArrows = YES;
    self.browser.displaySelectionButtons = NO;
    self.browser.zoomPhotosToFill = YES;
    self.browser.alwaysShowControls = YES;
    self.browser.enableGrid = NO;
    self.browser.startOnGrid = NO;
    self.browser.wantsFullScreenLayout = NO;

    [self.browser showNextPhotoAnimated:YES];
    [self.browser showPreviousPhotoAnimated:YES];

    [self loadImages];
}

- (void)loadImages
{
    self.images = [[NSMutableArray alloc] init];
    self.browserImages = [[NSMutableArray alloc] init];

    NSURL *url = [NSURL URLWithString:[NSString stringWithFormat:@"%@%@", HOST_URL, @"All_Images.php"]];
    NSData *jsonResults = [NSData dataWithContentsOfURL:url];
    NSDictionary *results = [NSJSONSerialization JSONObjectWithData:jsonResults options:0 error:NULL];

    NSDictionary *images = results[@"Images"];
    for (NSDictionary *img in images) {
        Image *imageObj = [[Image alloc] init];
        imageObj.imageId = [img objectForKey:@"id"];
        imageObj.imageName = [img objectForKey:@"name"];

        // Get the full image path
        NSString *fullImagePath = [NSString stringWithFormat:@"%@%@", HOST_URL, [img objectForKey:@"full_image"]];
        imageObj.imagePath = fullImagePath;

        // Get the thumbnail image path depending on the device
        NSString *thumbnailPath;
        if (DEVICE_IS_PAD) {
            thumbnailPath = [NSString stringWithFormat:@"%@%@", HOST_URL, [img objectForKey:@"thumbnail_ipad"]];
        } else {
            thumbnailPath = [NSString stringWithFormat:@"%@%@", HOST_URL, [img objectForKey:@"thumbnail_iphone"]];
        }
        imageObj.imageThumbnail = thumbnailPath;

        // Creates an object for each image and fill it with the retrieved info
        [self.images addObject:imageObj];

        // This array stores the image paths for later use (displaying them in a photo browser)
        MWPhoto *browserImage = [MWPhoto photoWithURL:[NSURL URLWithString:imageObj.imagePath]];
        browserImage.caption = imageObj.imageName;
        [self.browserImages addObject:browserImage];
    }
    [self.collectionView reloadData];
}

#pragma mark - MWPhotoBrowserDelegate
- (NSUInteger)numberOfPhotosInPhotoBrowser:(MWPhotoBrowser *)photoBrowser
{
    return self.browserImages.count;
}

- (id <MWPhoto>)photoBrowser:(MWPhotoBrowser *)photoBrowser photoAtIndex:(NSUInteger)index
{
    if (index < self.browserImages.count) {
        return self.browserImages[index];
    }
    return nil;
}

#pragma mark - UICollectionViewDataSource
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
{
    return self.images.count;
}

- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView
{
    return 1;
}

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *CellIdentifier = @"ImageCell";
    ImageCell *cell = (ImageCell *)[collectionView dequeueReusableCellWithReuseIdentifier:CellIdentifier forIndexPath:indexPath];

    Image *image = self.images[indexPath.row];
    [cell.imageView setImageWithURL:[NSURL URLWithString:image.imageThumbnail] placeholderImage:[UIImage imageNamed:@"placeholder"]];

    return cell;
}

#pragma mark - UICollectionViewDelegate
- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath
{
    // Opens the image browser
    [self.browser setCurrentPhotoIndex:indexPath.row];
    [self.navigationController pushViewController:self.browser animated:YES];
}

@end

I cannot find out why it shows the last image of the grid the first time I select an image. I have uploaded a demo project with the issue so it'll be easier for you to take a quick look at it. https://www.dropbox.com/s/tp6a67f83l0rzin/PhotoBrowserTest.zip

I'd really appreciate anyone's help to correct this problem.

Thank you.

Answer 1

Change in your project these methods

- (NSUInteger)numberOfPhotos {
   if (_photoCount == NSNotFound || _photoCount == 0) {
       if ([_delegate respondsToSelector:@selector(numberOfPhotosInPhotoBrowser:)]) {
           _photoCount = [_delegate numberOfPhotosInPhotoBrowser:self];
       } else if (_depreciatedPhotoData) {
        _photoCount = _depreciatedPhotoData.count;
       }
   }
   if (_photoCount == NSNotFound) _photoCount = 0;
   return _photoCount;
}

AND

- (id)initWithDelegate:(id <MWPhotoBrowserDelegate>)delegate {
    if ((self = [self init])) {
        _delegate = delegate;
        [self setCurrentPhotoIndex:0];
    }
    return self;
}

You need to check if your _photoCount == 0, because the first time you don´t have this info and _photoCount will be 0, but the second time your numberOfPhotosInPhotoBrowser will be the right