滚动UICollectionView时会加载重复数据

嗨，我是iOS的初学者，在我的项目中，我已经UICollectionView编程方式创建了UICollectionView ，确定它正常工作。

但在这里我的问题是当我滚动CollectionView重复数据加载时，如下面的屏幕所示。

我在这做错了什么？

为什么在滚动CollectionView时加载重复数据？

请帮帮我。

我的代码： –

 #import "ViewController.h" @interface ViewController () { UICollectionView *_collectionView; NSArray * images; NSArray * description; UILabel * NameLabel; UIImageView *image; } @end @implementation ViewController - (void)viewDidLoad { [super viewDidLoad]; images = [NSArray arrayWithObjects:@"angry_birds_cake.jpg", @"creme_brelee.jpg", @"egg_benedict.jpg", @"full_breakfast.jpg", @"green_tea.jpg", @"ham_and_cheese_panini.jpg", @"ham_and_egg_sandwich.jpg", @"hamburger.jpg", @"instant_noodle_with_egg.jpg", @"japanese_noodle_with_pork.jpg", @"mushroom_risotto.jpg", @"noodle_with_bbq_pork.jpg", @"starbucks_coffee.jpg", @"thai_shrimp_cake.jpg", @"vegetable_curry.jpg", @"white_chocolate_donut.jpg", nil]; description = [NSArray arrayWithObjects:@"angry_birds_cake.jpg", @"creme_brelee.jpg", @"egg_benedict.jpg", @"full_breakfast.jpg", @"green_tea.jpg", @"ham_and_cheese_panini.jpg", @"ham_and_egg_sandwich.jpg", @"hamburger.jpg", @"instant_noodle_with_egg.jpg", @"japanese_noodle_with_pork.jpg", @"mushroom_risotto.jpg", @"noodle_with_bbq_pork.jpg", @"starbucks_coffee.jpg", @"thai_shrimp_cake.jpg", @"vegetable_curry.jpg", @"white_chocolate_donut.jpg", nil]; UICollectionViewFlowLayout *layout=[[UICollectionViewFlowLayout alloc] init]; _collectionView = [[UICollectionView alloc]initWithFrame:CGRectMake(0, 0, 320, 480) collectionViewLayout:layout]; [_collectionView setDataSource:self]; [_collectionView setDelegate:self]; [_collectionView registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:@"cellIdentifier"]; [_collectionView registerClass:[UICollectionReusableView class] forSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:@"HeaderView"]; [_collectionView setBackgroundColor:[UIColor clearColor]]; self.view.backgroundColor = [UIColor whiteColor]; [self.view addSubview:_collectionView]; } - (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section{ return images.count; } - (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{ UICollectionViewCell *cell; if (cell == nil) { cell=[collectionView dequeueReusableCellWithReuseIdentifier:@"cellIdentifier" forIndexPath:indexPath]; image =[[UIImageView alloc]init]; [cell.contentView addSubview:image]; NameLabel = [[UILabel alloc]init]; NameLabel.textColor = [UIColor blackColor]; NameLabel.font = [UIFont systemFontOfSize:15.0]; [cell.contentView addSubview:NameLabel]; [image mas_makeConstraints:^(MASConstraintMaker *make) { make.centerX.equalTo(cell.contentView); make.centerY.equalTo(cell.contentView); make.width.equalTo(@40); make.height.equalTo(@40); }]; [NameLabel mas_makeConstraints:^(MASConstraintMaker *make) { make.top.equalTo(image).offset(35); make.left.equalTo(@5); make.width.equalTo(@80); make.height.equalTo(@40); }]; } image.image=[UIImage imageNamed:[images objectAtIndex:indexPath.row]]; NameLabel.text = [description objectAtIndex:indexPath.row]; cell.backgroundColor=[UIColor clearColor]; return cell; } - (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath{ return CGSizeMake(70, 70); } - (UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout insetForSectionAtIndex:(NSInteger)section{ UIEdgeInsets insets=UIEdgeInsetsMake(10, 10, 10, 10); return insets; } - (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout minimumLineSpacingForSectionAtIndex:(NSInteger)section { return 30.0; } 

Answer 1

– >将此代码放在创建UIImageView对象的行上方

 for (id subview in cell.contentView.subviews) { if ([subview isKindOfClass:[UIImageView class]]) { [subview removeFromSuperview]; } else if ([subview isKindOfClass:[UILabel class]]) { [subview removeFromSuperview]; } } 

• 它将删除UILabel和UIImageView类型的内容视图的子视图。

使用标签：

根据UIImageView的代码向视图添加标记

 self.image.tag = 101; 

对于UILabel

  self.NameLabel.tag = 102; 

使用标记删除视图

 //remove image view UIView *view = [cell.contentView viewWithTag:101]; [view removeFromSuperview]; //remove label view = [cell.contentView viewWithTag:101]; [view removeFromSuperview]; 

Answer 2

在if (cell == nil)条件下移动你的单元格子视图。

 if (cell == nil) { cell=[collectionView dequeueReusableCellWithReuseIdentifier:@"cellIdentifier" forIndexPath:indexPath]; UIImageView *image =[[UIImageView alloc]init]; [cell.contentView addSubview:image]; UILabel * NameLabel = [[UILabel alloc]init]; NameLabel.textColor = [UIColor blackColor]; NameLabel.font = [UIFont systemFontOfSize:15.0]; [cell.contentView addSubview:NameLabel]; [image mas_makeConstraints:^(MASConstraintMaker *make) { make.centerX.equalTo(cell.contentView); make.centerY.equalTo(cell.contentView); make.width.equalTo(@40); make.height.equalTo(@40); }]; [NameLabel mas_makeConstraints:^(MASConstraintMaker *make) { make.top.equalTo(image).offset(35); make.left.equalTo(@5); make.width.equalTo(@80); make.height.equalTo(@40); }]; } image.image=[UIImage imageNamed:[images objectAtIndex:indexPath.row]]; NameLabel.text = [description objectAtIndex:indexPath.row]; 

如果你将创建放在它之外，每次重复使用单元格时都会重新绘制它。