Question

问题：

我有一个CollectionView，它将UIimage加载到每个单元格中。但是我的问题是，当我加载包含更多图像的其他单元格时，它们似乎会重复。我无法在我的代码中看到可能导致这种情况的原因。可能是因为可重复使用的细胞存在一些问题？

有人能看出为什么会这样吗？

注意：包含图片的数组没有重复

问题视频 https://www.youtube.com/watch?v=vjRsFc8DDmI

问题图片：

以下是我的collectionView函数：

func collectionView(collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
    //#warning Incomplete method implementation -- Return the number of items in the section
    if self.movies == nil
    {
      return 0

    }

    return self.movies!.count

}

func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell 
{
    let cell =    
      collectionView.dequeueReusableCellWithReuseIdentifier(reuseIdentifier, 
        forIndexPath: indexPath) as! UpcomingCollectionViewCell

   if self.movies != nil && self.movies!.count >= indexPath.row
    {
        // Calc size of cell
        cell.frame.size.width = screenWidth / 3
        cell.frame.size.height = screenWidth / 3 * 1.54

        let movies = self.movies![indexPath.row]
        if(movies.posterPath != "" || movies.posterPath != "null"){
        cell.data = movies.posterPath
        }
        else{
        cell.data = nil
        }
        // See if we need to load more movies
        let rowsToLoadFromBottom = 5;
        let rowsLoaded = self.movies!.count
        if (!self.isLoadingMovies && (indexPath.row >= (rowsLoaded - rowsToLoadFromBottom)))
        {
            let totalRows = self.movieWrapper!.totalResults!
            let remainingMoviesToLoad = totalRows - rowsLoaded;
            if (remainingMoviesToLoad > 0)
            {
                self.loadMoreMovies()
            }
        }
}
   else
{
        cell.data = nil
}

    return cell
}

func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAtIndexPath indexPath: NSIndexPath) -> CGSize
{
    return CGSize(width: screenWidth/3, height: screenWidth/3*1.54)
}

这里我从Wrapper类中加载数据：

func loadFirstMovies()
{

    isLoadingMovies = true

    Movies.getMovies({ (movieWrapper, error) in
        if error != nil
        {
            // TODO: improved error handling
            self.isLoadingMovies = false
            let alert = UIAlertController(title: "Error", message: "Could not load first movies \(error?.localizedDescription)", preferredStyle: UIAlertControllerStyle.Alert)
            alert.addAction(UIAlertAction(title: "Click", style: UIAlertActionStyle.Default, handler: nil))
            self.presentViewController(alert, animated: true, completion: nil)
        }
        self.addMoviesFromWrapper(movieWrapper)
        self.activityIndicator.hidden = true
        self.isLoadingMovies = false
        self.collectionView.reloadData()
    })
}

func loadMoreMovies(){

    self.isLoadingMovies = true
    if self.movies != nil && self.movieWrapper != nil && self.movieWrapper!.page < self.movieWrapper!.totalPages
    {
        // there are more species out there!
        Movies.getMoreMovies(self.movieWrapper, completionHandler: { (moreWrapper, error) in
            if error != nil
            {
                // TODO: improved error handling
                self.isLoadingMovies = false
                let alert = UIAlertController(title: "Error", message: "Could not load more movies \(error?.localizedDescription)", preferredStyle: UIAlertControllerStyle.Alert)
                alert.addAction(UIAlertAction(title: "Click", style: UIAlertActionStyle.Default, handler: nil))
                self.presentViewController(alert, animated: true, completion: nil)
            }
            print("got more!")
            self.addMoviesFromWrapper(moreWrapper)
            self.isLoadingMovies = false
            self.collectionView.reloadData()
        })
    }
}

func addMoviesFromWrapper(wrapper: MovieWrapper?)
{
    self.movieWrapper = wrapper
    if self.movies == nil
    {
        self.movies = self.movieWrapper?.results
    }
    else if self.movieWrapper != nil && self.movieWrapper!.results != nil
    {
        self.movies = self.movies! + self.movieWrapper!.results!
    }
}

最后我在loadFirstMovies()

中致电：viewDidLoad()

编辑： UpcomingCollectionViewCell

class UpcomingCollectionViewCell: UICollectionViewCell {

@IBOutlet weak var imageView: UIImageView!


var data:String?{
    didSet{
        self.setupData()
    }
}

func setupData(){

   self.imageView.image = nil // reset the image

    if let urlString = data{
        let url =  NSURL(string: "http://image.tmdb.org/t/p/w342/" + urlString)
        self.imageView.hnk_setImageFromURL(url!)


      }
    }  
 }

Answer 1

这是典型的表格视图/集合视图设置问题。

每次使用dequeueReusableCellWithReuseIdentifier:等出列方法回收单元格时，必须始终完全配置单元格中的所有视图，包括将所有文本字段/图像视图设置为其起始值。您的代码有几个if语句，如果if的条件为false，则不要在单元格中设置视图。如果上次使用单元格时遗留了内容，则需要使用else子句从单元格视图中清除旧内容。

**编辑：

将cellForItemAtIndexPath方法改为开头，如下所示：

func collectionView(collectionView: UICollectionView, 
  cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell 
{
    let cell =    
      collectionView.dequeueReusableCellWithReuseIdentifier(reuseIdentifier, 
        forIndexPath: indexPath) as! UpcomingCollectionViewCell
    cell.imageView.image = nil;  //Remove the image from the recycled cell
//The rest of your method ...

Answer 2

在您的自定义单元格setupData()方法中尝试以下操作：

func setupData(){
  self.imageView.image = nil // reset the image

  if let urlString = data{
    let url =  NSURL(string: "http://image.tmdb.org/t/p/w342/" + urlString)
    self.imageView.hnk_setImageFromURL(url!)
  }
}

加载更多数据时CollectionView复制单元格

2 个答案: