ios - Tap Gesture Recognizer 落后一次

Question

我有一个 collectionView 照片，当点击照片时它应该显示该照片的详细 View 。

问题是，我点按的第一张照片没有任何作用，之后的每一次点按都起作用，除了显示两次前点按的照片。

例如:

点击照片 1...什么都不做。

点按照片 2... 显示照片 1。

点击照片 6...显示照片 2。

感谢您的帮助!

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

您无意中实现了 didDeselect 而不是 didSelect。如果您在键入时使用自动完成，这是一个很容易犯的错误，因为 didDeselect 按字母顺序排在第一位。