iOS-UICollectionViewController协议及回调

一.UICollectionViewDataSource

1.返回Section数量的方法

- (NSInteger)numberOfSectionsInCollectionView: (UICollectionView *)collectionView {
    return ;
}

2.返回每个Section中Cell的数量的方法

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

3.选择CollectionView中所使用的Cell

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

    //通过Cell重用标示符来获取Cell
    CollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier: reuseIdentifier
                                                                         forIndexPath: indexPath];
       return cell;
}

4.注册UICollectionReusableView的方法。

UINib *headerNib = [UINib nibWithNibName: @"CollectionHeaderReusableView"
                                      bundle: [NSBundle mainBundle]];
     //注册重用View
    [self.collectionView registerNib: headerNib
          forSupplementaryViewOfKind: UICollectionElementKindSectionHeader
                 withReuseIdentifier: @"CollectionHeaderReusableView"];

     //注册FooterView
    UINib *footerNib = [UINib nibWithNibName: @"CollectionFooterReusableView"
                                      bundle:[ NSBundle mainBundle]];

    [self.collectionView registerNib: footerNib
          forSupplementaryViewOfKind: UICollectionElementKindSectionFooter
                 withReuseIdentifier: @"CollectionFooterReusableView"];

5.在UICollectionViewDataSource中的设置Supplementary View

- (UICollectionReusableView *)collectionView: (UICollectionView *)collectionView
           viewForSupplementaryElementOfKind: (NSString *)kind
                                 atIndexPath: (NSIndexPath *)indexPath{
     //设置SectionHeader
    if ([kind isEqualToString: UICollectionElementKindSectionHeader]) {

        UICollectionReusableView *view = [collectionView dequeueReusableSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:@"CollectionHeaderReusableView" forIndexPath:indexPath];

        return view;
    }

    //设置SectionFooter
    UICollectionReusableView *view = [collectionView dequeueReusableSupplementaryViewOfKind:UICollectionElementKindSectionFooter withReuseIdentifier:@"CollectionFooterReusableView" forIndexPath:indexPath];
    return view;

}

二.UICollectionViewDelegateFlowLayout

1.Cell定制尺寸

- (CGSize)collectionView: (UICollectionView *)collectionView
                  layout: (UICollectionViewLayout*)collectionViewLayout
  sizeForItemAtIndexPath: (NSIndexPath *)indexPath{

    if (indexPath.section == ) {
        return CGSizeMake(, );
    }

    return CGSizeMake(, );
}

2.改变Section的上下左右边距--UIEdgeInsetsMake

- (UIEdgeInsets)collectionView: (UICollectionView *)collectionView
                        layout: (UICollectionViewLayout*)collectionViewLayout
        insetForSectionAtIndex: (NSInteger)section{

    if (section == ) {
        return UIEdgeInsetsMake(, , , );
    }
    return UIEdgeInsetsMake(, , , );
}

3.每个Cell的上下边距

- (CGFloat)collectionView: (UICollectionView *)collectionView
                   layout: (UICollectionViewLayout*)collectionViewLayout
minimumLineSpacingForSectionAtIndex: (NSInteger)section{
    if (section == ) {
        return 5.0f;
    }
    return 20.0f;
}

4.设置Cell的左右边距

- (CGFloat)collectionView: (UICollectionView *)collectionView
                   layout: (UICollectionViewLayout*)collectionViewLayout
minimumInteritemSpacingForSectionAtIndex: (NSInteger)section{
    if (section == ) {
        return 5.0f;
    }
    return 20.0f;
}

5.设置Header View和Footer View的大小

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

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

三.UICollectionViewDelegate

1.设置Cell可以高亮

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

    return YES;

}

2.Cell从非高亮变为高亮状态和从高亮变为非高亮状态时回调用下面的方法

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

    [self changeHighlightCellWithIndexPath:indexPath];
}

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

    [self changeHighlightCellWithIndexPath:indexPath];

}

3.设定Cell是否可选

- (BOOL)collectionView:(UICollectionView *)collectionView shouldSelectItemAtIndexPath:(NSIndexPath *)indexPath{
    return YES;
}

4.Cell支持多选

 self.collectionView.allowsMultipleSelection = YES;

5.在多选状态下需要支持取消Cell的多选

- (BOOL)collectionView:(UICollectionView *)collectionView shouldDeselectItemAtIndexPath:(NSIndexPath *)indexPath{
    return YES;
}

6.Cell将要出现，Cell出现后，Supplementary View将要出现以及Supplementary View已经出现

/**
 * Cell将要出现的时候调用该方法
 */
- (void)collectionView:(UICollectionView *)collectionView willDisplayCell:(UICollectionViewCell *)cell forItemAtIndexPath:(NSIndexPath *)indexPath NS_AVAILABLE_IOS(8_0){
    NSLog(@"第%ld个Section上第%ld个Cell将要出现",indexPath.section ,indexPath.row);
}

/**
 * Cell出现后调用该方法
 */
- (void)collectionView:(UICollectionView *)collectionView didEndDisplayingCell:(UICollectionViewCell *)cell forItemAtIndexPath:(NSIndexPath *)indexPath{
    NSLog(@"第%ld个Section上第%ld个Cell已经出现",indexPath.section ,indexPath.row);
}

/**
 * headerView或者footerView将要出现的时候调用该方法
 */
- (void)collectionView:(UICollectionView *)collectionView willDisplaySupplementaryView:(UICollectionReusableView *)view forElementKind:(NSString *)elementKind atIndexPath:(NSIndexPath *)indexPath NS_AVAILABLE_IOS(8_0){

    NSLog(@"第%ld个Section上第%ld个扩展View将要出现",indexPath.section ,indexPath.row);

}

/**
 * headerView或者footerView出现后调用该方法
 */
- (void)collectionView:(UICollectionView *)collectionView didEndDisplayingSupplementaryView:(UICollectionReusableView *)view forElementOfKind:(NSString *)elementKind atIndexPath:(NSIndexPath *)indexPath{

    NSLog(@"第%ld个Section上第%ld个扩展View已经出现",indexPath.section ,indexPath.row);

}