Tap Gesture Recognizer is one tap behind - ios

Question

I have a collectionView of Photos, when the photo is tapped it should show a detail view of that photo.
The problem is, the first photo I tap doesn't do anything, and then every tap after works except it shows the photo tapped two times ago.
For example:
Tap Photo 1... does nothing.
Tap Photo 2... shows Photo 1.
Tap Photo 6... shows Photo 2.
Thanks for the help!
ViewController.m
#property (nonatomic) NSArray *photos;
- (void)viewDidLoad
{
[super viewDidLoad];
[self.collectionView registerClass:[BlissPhotoCell class]
forCellWithReuseIdentifier:#"photo"];
NSURLSession *session = [NSURLSession sharedSession];
NSString *urlString = [[NSString alloc] initWithFormat:#"https://api.instagram.com/v1/;
NSURL *url = [[NSURL alloc]initWithString:urlString];
NSURLRequest *request = [[NSURLRequest alloc] initWithURL:url];
NSURLSessionDownloadTask *task = [session downloadTaskWithRequest:request completionHandler:^(NSURL *location, NSURLResponse *response, NSError *error) {
NSString *text = [[NSString alloc] initWithContentsOfURL:location encoding:NSUTF8StringEncoding error:nil];
NSData *data = [[NSData alloc] initWithContentsOfURL:location];
NSDictionary *responseDictionary = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:nil];
self.photos = [responseDictionary valueForKeyPath:#"data"];
dispatch_async(dispatch_get_main_queue(), ^{
[self.collectionView reloadData];
});
}];
[task resume];
- (void)collectionView:(UICollectionView *)collectionView didDeselectItemAtIndexPath:(NSIndexPath *)indexPath {
NSDictionary *photo = self.photos[indexPath.row];
BlissDetailViewController *viewController = [[BlissDetailViewController alloc] init];
viewController.modalPresentationStyle = UIModalPresentationCustom;
viewController.transitioningDelegate = self;
viewController.photo = photo;
[self presentViewController:viewController animated:YES completion:nil];
}
BlissPresentDetailTransition.h
- (void)animateTransition:(id<UIViewControllerContextTransitioning>)transitionContext {
UIViewController *detail = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
UIView *containerView = [transitionContext containerView];
detail.view.alpha = 0.0;
CGRect frame = containerView.bounds;
frame.origin.y += 20.0;
frame.size.height -= 20.0;
detail.view.frame = frame;
[containerView addSubview:detail.view];
[UIView animateWithDuration:0.3 animations:^{
detail.view.alpha = 1.0;
} completion:^(BOOL finished) {
[transitionContext completeTransition:YES];
}];
}
- (NSTimeInterval)transitionDuration:(id<UIViewControllerContextTransitioning>)transitionContext {
return 0.3;
}

Answer 1

You inadvertently implemented didDeselect rather than didSelect. It's an easy mistake to make if you use auto completion when you type since didDeselect comes up first alphabetically.