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UICollectionView的使用（1） - 简单介绍
1.方法和属性
// 初始化
- (instancetype)initWithFrame:(CGRect)frame collectionViewLayout:(UICollectionViewLayout *)layout
// 代理
@property (nonatomic, weak, nullable) id <UICollectionViewDelegate> delegate;
@property (nonatomic, weak, nullable) id <UICollectionViewDataSource> dataSource;
// cell 非xib的注册方式
- (void)registerClass:(nullable Class)cellClass forCellWithReuseIdentifier:(NSString *)identifier;
// cell xib的注册方式
- (void)registerNib:(nullable UINib *)nib forCellWithReuseIdentifier:(NSString *)identifier;
//
- (void)registerClass:(nullable Class)viewClass forSupplementaryViewOfKind:(NSString *)elementKind withReuseIdentifier:(NSString *)identifier;
//
- (void)registerNib:(nullable UINib *)nib forSupplementaryViewOfKind:(NSString *)kind withReuseIdentifier:(NSString *)identifier;
// cell 的重用机制 在代理方法里添加(- (__kindof UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath;
)
- (__kindof UICollectionViewCell *)dequeueReusableCellWithReuseIdentifier:(NSString *)identifier forIndexPath:(NSIndexPath *)indexPath;
// Supplement View 的重用机制 在代理方法(- (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath;)
- (__kindof UICollectionReusableView *)dequeueReusableSupplementaryViewOfKind:(NSString *)elementKind withReuseIdentifier:(NSString *)identifier forIndexPath:(NSIndexPath *)indexPath;
2.代理方法
UICollectionViewDataSource
@protocol UICollectionViewDataSource <NSObject>
@end
必须重写的方法
// 每个section 分区的item的个数.
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section;
// The cell that is returned must be retrieved from a call to -dequeueReusableCellWithReuseIdentifier:forIndexPath:
// 返回一个cell ,这个cell 是调用 dequeueReusableCellWithReuseIdentifier:forIndexPath: 得到的可以重用的cell
- (__kindof UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath;
可选方法
// 返回 section 个数
- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView;
// The view that is returned must be retrieved from a call to -dequeueReusableSupplementaryViewOfKind:withReuseIdentifier:forIndexPath:
// 添加追加视图的内容的时候的使用.
// 返回一个view,这个view是调用 dequeueReusableSupplementaryViewOfKind:withReuseIdentifier:forIndexPath:方法获取的可重用的view
- (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath;
// 设置某个item是否可以被移动，返回NO则不能移动
- (BOOL)collectionView:(UICollectionView *)collectionView canMoveItemAtIndexPath:(NSIndexPath *)indexPath NS_AVAILABLE_IOS(9_0);
// 移动哪个item
- (void)collectionView:(UICollectionView *)collectionView moveItemAtIndexPath:(NSIndexPath *)sourceIndexPath toIndexPath:(NSIndexPath*)destinationIndexPath NS_AVAILABLE_IOS(9_0);
#TODO: 关于 index view 的内容
/// Returns a list of index titles to display in the index view (e.g. ["A", "B", "C" ... "Z", "#"])
// 在 index view 添加内容
- (nullable NSArray<NSString *> *)indexTitlesForCollectionView:(UICollectionView *)collectionView API_AVAILABLE(tvos(10.2));
/// Returns the index path that corresponds to the given title / index. (e.g. "B",1)
/// Return an index path with a single index to indicate an entire section, instead of a specific item.
// 获取到index view 上title内容相同的NSIndexPath .
- (NSIndexPath *)collectionView:(UICollectionView *)collectionView indexPathForIndexTitle:(NSString *)title atIndex:(NSInteger)index API_AVAILABLE(tvos(10.2));
UICollectionViewDelegate
和数据无关的交互以及view展示,比如cell的展示,高亮,长按菜单等.
@protocol UICollectionViewDelegate <UIScrollViewDelegate>
@end
全部是可选方法
// Methods for notification of selection/deselection and highlight/unhighlight events.
// The sequence of calls leading to selection from a user touch is:
//
// (when the touch begins)
// 1. -collectionView:shouldHighlightItemAtIndexPath:
// 2. -collectionView:didHighlightItemAtIndexPath:
//
// (when the touch lifts)
// 3. -collectionView:shouldSelectItemAtIndexPath: or -collectionView:shouldDeselectItemAtIndexPath:
// 4. -collectionView:didSelectItemAtIndexPath: or -collectionView:didDeselectItemAtIndexPath:
// 5. -collectionView:didUnhighlightItemAtIndexPath:
#TODO: 关于item的高亮
// 设置是否允许某个Item高亮
- (BOOL)collectionView:(UICollectionView *)collectionView shouldHighlightItemAtIndexPath:(NSIndexPath *)indexPath;
// 当高亮是,触发的回调方法
- (void)collectionView:(UICollectionView *)collectionView didHighlightItemAtIndexPath:(NSIndexPath *)indexPath;
// 当结束高亮触发的方法
- (void)collectionView:(UICollectionView *)collectionView didUnhighlightItemAtIndexPath:(NSIndexPath *)indexPath;
#TODO: 关于选择Item
// 是否允许选中某个 item
- (BOOL)collectionView:(UICollectionView *)collectionView shouldSelectItemAtIndexPath:(NSIndexPath *)indexPath;
// 是否允许取消选中某个item的方法.
- (BOOL)collectionView:(UICollectionView *)collectionView shouldDeselectItemAtIndexPath:(NSIndexPath *)indexPath; // called when the user taps on an already-selected item in multi-select mode
// 当选中某个item时触发的方法
- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath;
// 当取消选中某个item时触发的方法
- (void)collectionView:(UICollectionView *)collectionView didDeselectItemAtIndexPath:(NSIndexPath *)indexPath;
#TODO: 关于显示(display)的方法
//将要显示item时调用的方法
- (void)collectionView:(UICollectionView *)collectionView willDisplayCell:(UICollectionViewCell *)cell forItemAtIndexPath:(NSIndexPath *)indexPath NS_AVAILABLE_IOS(8_0);
//将要显示追加视图调用的方法
- (void)collectionView:(UICollectionView *)collectionView willDisplaySupplementaryView:(UICollectionReusableView *)view forElementKind:(NSString *)elementKind atIndexPath:(NSIndexPath *)indexPath NS_AVAILABLE_IOS(8_0);
//结束显示item时调用的方法
- (void)collectionView:(UICollectionView *)collectionView didEndDisplayingCell:(UICollectionViewCell *)cell forItemAtIndexPath:(NSIndexPath *)indexPath;
//结束显示追加视图调用的方法
- (void)collectionView:(UICollectionView *)collectionView didEndDisplayingSupplementaryView:(UICollectionReusableView *)view forElementOfKind:(NSString *)elementKind atIndexPath:(NSIndexPath *)indexPath;
// These methods provide support for copy/paste actions on cells.
// All three should be implemented if any are.
#TODO: 关于长按菜单操作的方法
// 设置是否展示长按菜单
- (BOOL)collectionView:(UICollectionView *)collectionView shouldShowMenuForItemAtIndexPath:(NSIndexPath *)indexPath;
// 设置长按菜单的选项
- (BOOL)collectionView:(UICollectionView *)collectionView canPerformAction:(SEL)action forItemAtIndexPath:(NSIndexPath *)indexPath withSender:(nullable id)sender;
// 实现点击菜单按钮后的触发方法,copy，cut和paste等方法可以使用
- (void)collectionView:(UICollectionView *)collectionView performAction:(SEL)action forItemAtIndexPath:(NSIndexPath *)indexPath withSender:(nullable id)sender;
// support for custom transition layout
#TODO: 关于自定义转换布局时调用
- (nonnull UICollectionViewTransitionLayout *)collectionView:(UICollectionView *)collectionView transitionLayoutForOldLayout:(UICollectionViewLayout *)fromLayout newLayout:(UICollectionViewLayout *)toLayout;
// Focus
#TODO: 聚焦 iOS 9.0 新方法
// 是否某个item需要焦点
- (BOOL)collectionView:(UICollectionView *)collectionView canFocusItemAtIndexPath:(NSIndexPath *)indexPath NS_AVAILABLE_IOS(9_0);
// 是否要更新内容的焦点
- (BOOL)collectionView:(UICollectionView *)collectionView shouldUpdateFocusInContext:(UICollectionViewFocusUpdateContext *)context NS_AVAILABLE_IOS(9_0);
// 已经更新焦点时调用的方法
- (void)collectionView:(UICollectionView *)collectionView didUpdateFocusInContext:(UICollectionViewFocusUpdateContext *)context withAnimationCoordinator:(UIFocusAnimationCoordinator *)coordinator NS_AVAILABLE_IOS(9_0);
//放回上一个焦点的indexPath
- (nullable NSIndexPath *)indexPathForPreferredFocusedViewInCollectionView:(UICollectionView *)collectionView NS_AVAILABLE_IOS(9_0);
#TODO : 移动item从originalIndexPath到proposedIndexPath
- (NSIndexPath *)collectionView:(UICollectionView *)collectionView targetIndexPathForMoveFromItemAtIndexPath:(NSIndexPath *)originalIndexPath toProposedIndexPath:(NSIndexPath *)proposedIndexPath NS_AVAILABLE_IOS(9_0);
//item
- (CGPoint)collectionView:(UICollectionView *)collectionView targetContentOffsetForProposedContentOffset:(CGPoint)proposedContentOffset NS_AVAILABLE_IOS(9_0); // customize the content offset to be applied during transition or update animations
