在集合视图中滚动时选择了多个单元格 [英] Multiple Cells selected on scrolling in collection view

问题描述

我在集合视图中面临以下问题:
问题 1. 每当我在顶部单元格中选择一个项目并滚动到底部时，也会选择底部的另一个项目:

I am facing following problems in collection view :
Problem 1. Whenever I select an item in the top cells and scroll to bottom, another item at bottom is also selected :

滚动后

After Scrolling

问题2:现在在第一个场景之后，如果我向上滚动并选择另一个单元格，那么之前选择的单元格仍然不会改变背景.

Problem 2 : Now after the first scenario, if I scroll up and select another cell, then the previously selected cell still does not change the background.

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{
    //Cell from the prototype
    _appliancesViewCell = [collectionView dequeueReusableCellWithReuseIdentifier:@"AppliancesCell" forIndexPath:indexPath];

    NSLog(@"IndexPath.row = %ld .item %ld",indexPath.row,indexPath.item);
    if(indexPath.row == self.selectedRow){
        _appliancesViewCell.contentView.backgroundColor = UIColorFromRGB(0xd3d3d3);
    }else{
         _appliancesViewCell.contentView.backgroundColor = [UIColor whiteColor];
    }

    Appliance *appliances = [_appliancesArray objectAtIndex:indexPath.row];
    _appliancesViewCell.applianceImage.image = appliances.applianceImage;
    _appliancesViewCell.applianceName.text = appliances.applianceName;
    _appliancesViewCell.applianceName.textColor =[UIColor textPrimaryColor];
    _appliancesViewCell.layer.borderColor = UIColorFromRGB(0x9b9b9b).CGColor;
    _appliancesViewCell.layer.borderWidth = 1.0;
    _appliancesViewCell.layer.shadowRadius = 2.0;

    return _appliancesViewCell;
}



- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath{
    UICollectionViewCell *selectedCell = [collectionView cellForItemAtIndexPath:indexPath];
    selectedCell.contentView.backgroundColor = UIColorFromRGB(0xd3d3d3);
    self.selectedRow = indexPath.row;
    Appliance *appliance_selected =  _appliancesArray[indexPath.row];
    _detailsArray = appliance_selected.descriptionsArray;
}


- (void)collectionView:(UICollectionView *)collectionView didDeselectItemAtIndexPath:(NSIndexPath *)indexPath{
    UICollectionViewCell *selectedCell = [collectionView cellForItemAtIndexPath:indexPath];
    selectedCell.contentView.backgroundColor = [UIColor whiteColor];
}

请让我知道我哪里出错了，是改变颜色的逻辑，还是我遗漏了什么.

Please let me know where I am going wrong, is the logic of changing colors, or I am missing something.

推荐答案

因为单元格被重复使用，这就是它产生问题的原因.最好这样使用:

Because the cells are being reused that's why it's making a problem. Better use like this:

-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {

   static NSString *cellIdentifier = @"AppliancesCell";

  _appliancesViewCell = [collectionView dequeueReusableCellWithReuseIdentifier:cellIdentifier forIndexPath:indexPath];

   collectionView.allowsMultipleSelection = YES;
   if ([cell isSelected]) {
      _appliancesViewCell.contentView.backgroundColor = [UIColor blackColor];
   }else {
      _appliancesViewCell.contentView.backgroundColor = [UIColor clearColor];
   }
   return cell;
}

 -(void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath {

    _appliancesViewCell = (CategoryListCollectionViewCell *)[collectionView cellForItemAtIndexPath:indexPath];

    _appliancesViewCell.contentView.backgroundColor = [UIColor blackColor];

}

- (BOOL)collectionView:(UICollectionView *)collectionView shouldDeselectItemAtIndexPath:(NSIndexPath *)indexPath {

     return YES;
}

-(void)collectionView:(UICollectionView *)collectionView didDeselectItemAtIndexPath:(NSIndexPath *)indexPath {

    _appliancesViewCell = (CategoryListCollectionViewCell *)[collectionView cellForItemAtIndexPath:indexPath];

    _appliancesViewCell.contentView.backgroundColor = [UIColor clearColor];
}

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