iOS开发 ----- UICollectionView

UICollectionView

简介

和tableView类似的控件,但更零活,tableView是以行为单位的,而collectionView是item,可大可小,对于复杂的布局来说,更加零活

代理

UICollectionViewDataSourceUICollectionViewDelegateUICollectionViewDelegateFlowLayout

使用方法步骤

1. 指定布局

//首先用 UICollectionViewFlowLayout来指定方向,水平或者垂直    UICollectionViewFlowLayout * flow = [[UICollectionViewFlowLayout alloc]init];    /*         UICollectionViewScrollDirectionVertical,     UICollectionViewScrollDirectionHorizontal     */    //设置为纵向滚动    flow.scrollDirection = UICollectionViewScrollDirectionVertical;

2. 初始化

_collertionView = [[UICollectionView alloc]initWithFrame:CGRectMake(0, 0, [UIScreen mainScreen].bounds.size.width, [UIScreen mainScreen].bounds.size.height) collectionViewLayout:flow];

3. 遵守代理协议

    _collertionView.delegate = self;    _collertionView.dataSource = self;

4. 使用某个指定的cell,提前声明

[_collertionView registerClass:[MyCollectionViewCell class] forCellWithReuseIdentifier:@"cellID"];

5. 声明标头,标尾,可以从xib文件声明布局,手写代码也是没问题的

    [_collertionView registerNib:[UINib nibWithNibName:@"HeaderCollectionReusableView" bundle:nil] forSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:@"header"];    [_collertionView registerNib:[UINib nibWithNibName:@"HeaderCollectionReusableView" bundle:nil] forSupplementaryViewOfKind:UICollectionElementKindSectionFooter             withReuseIdentifier:@"footer"];

6. 相关代理协议

6.1分区

-(NSInteger)numberOfSectionsInCollectionView:(nonnull UICollectionView *)collectionView{    return 2;}````<div class="se-preview-section-delimiter"></div>######6.2每个区有多少item<div class="se-preview-section-delimiter"></div>

-(NSInteger)collectionView:(nonnull UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
{
return 10;
}

<div class="se-preview-section-delimiter"></div>######6.3每个item的宽高<div class="se-preview-section-delimiter"></div>

//靠左侧的坐标原点是左上角
//靠右边的坐标原点是右上角
-(CGSize)collectionView:(nonnull UICollectionView )collectionView layout:(nonnull UICollectionViewLayout )collectionViewLayout sizeForItemAtIndexPath:(nonnull NSIndexPath *)indexPath
{

    return CGSizeMake(150, 150);

}

<div class="se-preview-section-delimiter"></div>######6.4 创建单元格 和tableView不同的时,这里时直接从队列里拿,不用重新创建,要保证id和注册的时候一样<div class="se-preview-section-delimiter"></div>

-(UICollectionViewCell )collectionView:(nonnull UICollectionView )collectionView cellForItemAtIndexPath:(nonnull NSIndexPath *)indexPath
{
//不用判断
static NSString * cellID = @”cellID”;
MyCollectionViewCell * cell = [collectionView dequeueReusableCellWithReuseIdentifier:cellID forIndexPath:indexPath];

cell.label.text = [NSString stringWithFormat:@"第%ld个",indexPath.row];cell.imageView.image = [UIImage imageNamed:[NSString stringWithFormat:@"10_%ld.jpg",indexPath.row]];return cell;

}

<div class="se-preview-section-delimiter"></div>######6.5 边距调整<div class="se-preview-section-delimiter"></div>

-(UIEdgeInsets)collectionView:(nonnull UICollectionView )collectionView layout:(nonnull UICollectionViewLayout )collectionViewLayout insetForSectionAtIndex:(NSInteger)section
{
return UIEdgeInsetsMake(5, 5, 5, 5);
}

<div class="se-preview-section-delimiter"></div>######6.5 设置标头,标尾 标头标尾有特定的id,调用系统的来设置<div class="se-preview-section-delimiter"></div>

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

HeaderCollectionReusableView * view = nil;if ([kind isEqualToString:UICollectionElementKindSectionHeader]) {    static NSString * header = @"header";    view = [collectionView dequeueReusableSupplementaryViewOfKind:UICollectionElementKindSectionHeader                                              withReuseIdentifier:header                                                     forIndexPath:indexPath];    view.label.text = @"1";}else{    static NSString * footer = @"footer";    view = [collectionView dequeueReusableSupplementaryViewOfKind:UICollectionElementKindSectionFooter                                              withReuseIdentifier:footer                                                     forIndexPath:indexPath];    view.label.text = @"2";}return view;

}

<div class="se-preview-section-delimiter"></div>######6.6 设置标头的大小<div class="se-preview-section-delimiter"></div>

-(CGSize)collectionView:(nonnull UICollectionView *)collectionView
layout:(nonnull UICollectionViewLayout *)collectionViewLayout referenceSizeForHeaderInSection:(NSInteger)section
{
return CGSizeMake(375, 40);
}

<div class="se-preview-section-delimiter"></div>######6.7设置标尾的大小<div class="se-preview-section-delimiter"></div>

-(CGSize)collectionView:(nonnull UICollectionView )collectionView layout:(nonnull UICollectionViewLayout )collectionViewLayout referenceSizeForFooterInSection:(NSInteger)section
{
return CGSizeMake(375, 40);
}

<div class="se-preview-section-delimiter"></div>######6.8 选中某一个item的方法<div class="se-preview-section-delimiter"></div>

-(void)collectionView:(nonnull UICollectionView )collectionView didSelectItemAtIndexPath:(nonnull NSIndexPath )indexPath
{
NSLog(@”%ld”,indexPath.row);
}

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