重新加载后无法取消选择 UICollectionView 单元格

Posted 2023-02-27

【中文标题】重新加载后无法取消选择 UICollectionView 单元格

【英文标题】：Unable To Deselect UICollectionView Cell once it is reloaded

【发布时间】：2013-07-18 18:47:07

【问题描述】：

我在使用 UIcollectionView 时遇到了一系列问题，我认为解决方法是当前导致问题的原因。

好的，所以我有一个集合视图，它从一个更新非常频繁的类中加载对象，可能每隔几秒钟。

我遇到的第一个问题；是当我选择一个单元格并突出显示它时，集合视图下方的另一个单元格也被突出显示。我的解决方案是创建一个选定单元数组并在新数组中运行一个循环来决定要突出显示的内容。

现在，重新加载集合视图时会出现问题。单元格继续保持突出显示并显示为选中状态，但它们没有注册触摸，因此我无法取消选择它。

    - (NSInteger)collectionView:(UICollectionView *)view numberOfItemsInSection:        (NSInteger)section

    return [self.deviceList count];


- (NSInteger)numberOfSectionsInCollectionView: (UICollectionView *)collectionView

    return 1;


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

    DeviceCollectionViewCell *cell = [self.deviceCollectionView dequeueReusableCellWithReuseIdentifier:@"DeviceCell" forIndexPath:indexPath];

    if([self.deviceList count] > indexPath.row)
    
        cell.device = [self.deviceList objectAtIndex:indexPath.row];
    

    if ([[self.deviceCollectionView indexPathsForSelectedItems] containsObject:indexPath]) 
        NSLog(@"does it ever?");

       // cell.backgroundColor = [UIColor blueColor];
    


    for (TDDeviceParser *device in self.selectedDevices)
    
        if ([cell.device.deviceTextRecord.serialNumber isEqualToString:device.deviceTextRecord.serialNumber])
        
            [cell setSelected:YES];
            break;
        
        else
        
            [cell setSelected:NO];
        
    
    return cell;


- (UICollectionReusableView *)collectionView: (UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath

    UICollectionReusableView *reusableview = nil;
    if (kind == UICollectionElementKindSectionHeader) 
        TitleHeaderForDeviceCollectionView *headerView = [collectionView dequeueReusableSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:@"HeaderView" forIndexPath:indexPath];
        reusableview = headerView;
    

    else if (kind == UICollectionElementKindSectionFooter) 
        LogoFooterForDeviceCollectionView *footerView = [collectionView dequeueReusableSupplementaryViewOfKind:UICollectionElementKindSectionFooter withReuseIdentifier:@"FooterView" forIndexPath:indexPath];
        reusableview = footerView;
    
    return reusableview;


#pragma mark - UICollectionViewDelegate
- (BOOL)collectionView:(UICollectionView *)collectionView shouldSelectItemAtIndexPath:(NSIndexPath *)indexPath

    //Iphone Five and Older Ipads: Max2
    int maxCount = 2;
    //ipad 4
    if ([[UIDeviceHardwareVersion platform] isEqualToString:@"iPad3,4"] || [[UIDeviceHardwareVersion platform] isEqualToString:@"iPad3,5"] || [[UIDeviceHardwareVersion platform] isEqualToString:@"iPad3,6"])
    
        maxCount = 4;
    
    //Ipod5th,Iphone4 & Iphone4s; Don't select, just play.
    else if ([[UIDeviceHardwareVersion platform] isEqualToString:@"iPod5,1"] ||  [[UIDeviceHardwareVersion platform] isEqualToString:@"iPhone4,1"]  ||  [[UIDeviceHardwareVersion platform] isEqualToString:@"iPhone3,1"]  ||  [[UIDeviceHardwareVersion platform] isEqualToString:@"iPhone3,2"]  ||  [[UIDeviceHardwareVersion platform] isEqualToString:@"iPhone3,3"])
    
        maxCount = 0;
        //Just play.
        [self.selectedDevices removeAllObjects];
        [self.selectedDevices addObject:[self.deviceList objectAtIndex:indexPath.row]];
        [[TDDeviceManager sharedInstance] removeObserver:self];
        [self performSegueWithIdentifier:@"VideoPlayer" sender:self];
    

    if (self.selectedDevices.count < maxCount)
    
        return YES;
    
    else
    
        return NO;
    


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




    [self.selectedDevices addObject:[self.deviceList objectAtIndex:indexPath.row]];
    [self updatePlayerImages];
    NSLog(@"device Count %d",self.selectedDevices.count);





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


    NSLog(@"Should I Deselect?");
    return YES;




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

    NSLog(@"%s",__PRETTY_FUNCTION__);
    //What device do we remove?
    for (TDDeviceParser *device in self.selectedDevices)
    
        if ([device.deviceTextRecord.serialNumber isEqualToString:((TDDeviceParser*)[self.deviceList objectAtIndex:indexPath.row]).deviceTextRecord.serialNumber])
        
             NSLog(@"%s Removed %@",__PRETTY_FUNCTION__, device.name);
            [self.selectedDevices removeObject:device];
            break;
        
    
     NSLog(@"%s Update %d",__PRETTY_FUNCTION__, self.selectedDevices.count);
    [self updatePlayerImages];

【参考方案1】：

我认为问题是单元格已被选中，但 CollectionView 不知道该单元格已被选中。我添加了（第二行）来解决问题。

        [cell setSelected:YES];
        [self.deviceCollectionView selectItemAtIndexPath:indexPath animated:NO scrollPosition:UICollectionViewScrollPositionNone];

【讨论】：

scrollPosition: 采用 UICollectionViewScrollPosition 类型的值，而不是 BOOL。 UICollectionViewScrollPositionNone 是要使用的正确值。

感谢 DTDev 的解决方案！我面临着完全相同的问题。