Question

我CollectionViews中有两个ViewController。我想同时在屏幕上同时显示两者，但由于某种原因，第二个CollectionView将不会显示任何单元格。

这就是我所拥有的：

    override func viewDidLoad() {
    super.viewDidLoad()

    mainView.popularCollection.dataSource = self
    mainView.popularCollection.delegate = self
    mainView.popularCollection.register(PopularMovieCell.self, forCellWithReuseIdentifier: popularCell)

    mainView.upcomingMoviesCollection.dataSource = self
    mainView.upcomingMoviesCollection.delegate = self
    mainView.upcomingMoviesCollection.register(UpcomingMovieCell.self, forCellWithReuseIdentifier: upcomingCell)

    //TODO: change popularMovies to trending movies.
    NetworkingManager.shared.getPopularMovies { (fetchedMovies) in
        self.fetchedPopularMovies = fetchedMovies
    }

    NetworkingManager.shared.getUpComingMovies { (upcomingMovies) in
        self.fetchedUpcomingMovies = upcomingMovies
    }
}

func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {        
    if collectionView == mainView.upcomingMoviesCollection {
        return fetchedUpcomingMovies.count
    }
    return fetchedPopularMovies.count
}

func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {

    if collectionView == mainView.upcomingMoviesCollection {
        let upComingCell = collectionView.dequeueReusableCell(withReuseIdentifier: upcomingCell, for: indexPath) as! UpcomingMovieCell
        let movie = self.fetchedUpcomingMovies[indexPath.row]

        if let poster = movie.poster_path {
            upComingCell.movieImage.loadImageUsingCacheWithUrlString(urlString: baseImgUrl + poster)
        }else {
            upComingCell.movieImage.image = UIImage(named: "placeholder")
        }
        upComingCell.movieNameLabel.text = movie.title
        upComingCell.movieReleasedate.text = movie.release_date

        return upComingCell
    }


    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: popularCell, for: indexPath) as! PopularMovieCell
    let movie = self.fetchedPopularMovies[indexPath.row]
    var genreString = ""

    if let poster = movie.poster_path {
        cell.movieImage.loadImageUsingCacheWithUrlString(urlString: baseImgUrl + poster)
    }else {
        cell.movieImage.image = UIImage(named: "placeholder")
    }
    cell.movieNameLabel.text = movie.title
    cell.ratingScoreLabel.text = String(movie.vote_average)

    //A movie may have few genres, so we get every genre code of the specific movie, translating it to a genre name, and adding it to one string.
    for genre in movie.genre_ids {
        if let genre = genresById[genre] {
            genreString = genreString + " " + genre + ", "
            genreString = genreString.trimmingCharacters(in: .whitespacesAndNewlines)
        }
    }
    //Removing the last char in the string if it is ","
    if genreString.last == "," {
        genreString.removeLast()
    }
    cell.movieGenre.text = genreString

    return cell
}

我看到这段代码是在几个类似问题中的正确答案，但是对我来说由于某些原因它是行不通的。

我检查了一下，然后进入fetchedUpcomingMoves.count，数字为0，但是在打印时却得到20。我不明白为什么它不起作用。

Answer 1

似乎您正在返回正确数量的单元格以及用于不同集合视图的单元格。我怀疑一个问题是：

获取数据的部分可能在不同的线程上，因此一旦获得数据，也许尝试更新集合视图？

NetworkingManager.shared.getPopularMovies { (fetchedMovies) in
    self.fetchedPopularMovies = fetchedMovies
    DispatchQueue.main.async {
        mainView.popularCollection.reloadData()
    }
}

NetworkingManager.shared.getUpComingMovies { (upcomingMovies) in
    self.fetchedUpcomingMovies = upcomingMovies
    DispatchQueue.main.async {
        mainView.upcomingCollection.reloadData()
    }
}

如果这不起作用，请继续

两个收藏夹视图，一个不会显示单元格

1 个答案: