Table View 和Collection View的使用
TableView是iOS开发中经常用到的一个组件，其重要程度可想而知。
Collection View提供了比Table View更多的空间来显示更多的内容。
数据源
顾名思义，为table view和 collection view提供数据的来源。
UITableViewDataSource
在以下的函数中可以实现对table view的数据来源的配置
/*配置table view*/
@ Required
//返回指定位置的table cell
- tableView:cellForRowAtIndexPath:
@ Required
//返回各个区中有多少行
- tableView:numberOfRowsInSection:
//返回这个table view中包含了多少个分区section
- numberOfSectionsInTableView:
//返回每个section的标题
- sectionIndexTitlesForTableView:
//返回有标题和分区标题索引的index
- tableView:sectionForSectionIndexTitle:atIndex:
//返回一个字符串来作为分区header的标题
- tableView:titleForHeaderInSection:
//返回一个字符串来作为分区footer的标题
- tableView:titleForFooterInSection:
/*插入和删除row*/
//对一个特定的row来进行删除或者插入操作
- tableView:commitEditingStyle:forRowAtIndexPath:
//返回一个布尔值来表示这行row是否可以被编辑
- tableView:canEditRowAtIndexPath:
/*对rows重新排序*/
//返回一个布尔值表示这行row是否可以被移动
- tableView:canMoveRowAtIndexPath:
//在这个方法里可以对特定的row进行移动
- tableView:moveRowAtIndexPath:toIndexPath:
UITableViewDelegate
通过该协议，可以对tableview的点击事件进行响应及对tableview进行配置。
// 显示定制
- (void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath;
- (void)tableView:(UITableView *)tableView willDisplayHeaderView:(UIView *)view forSection:(NSInteger)section NS_AVAILABLE_IOS(6_0);
- (void)tableView:(UITableView *)tableView willDisplayFooterView:(UIView *)view forSection:(NSInteger)section NS_AVAILABLE_IOS(6_0);
- (void)tableView:(UITableView *)tableView didEndDisplayingCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath*)indexPath NS_AVAILABLE_IOS(6_0);
- (void)tableView:(UITableView *)tableView didEndDisplayingHeaderView:(UIView *)view forSection:(NSInteger)section NS_AVAILABLE_IOS(6_0);
- (void)tableView:(UITableView *)tableView didEndDisplayingFooterView:(UIView *)view forSection:(NSInteger)section NS_AVAILABLE_IOS(6_0);
//可变的高度的支持
- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath;
- (CGFloat)tableView:(UITableView *)tableView heightForHeaderInSection:(NSInteger)section;
- (CGFloat)tableView:(UITableView *)tableView heightForFooterInSection:(NSInteger)section;
// Use the estimatedHeight methods to quickly calcuate guessed values which will allow for fast load times of the table.
// If these methods are implemented, the above -tableView:heightForXXX calls will be deferred until views are ready to be displayed, so more expensive logic can be placed there.
- (CGFloat)tableView:(UITableView *)tableView estimatedHeightForRowAtIndexPath:(NSIndexPath *)indexPath NS_AVAILABLE_IOS(7_0);
- (CGFloat)tableView:(UITableView *)tableView estimatedHeightForHeaderInSection:(NSInteger)section NS_AVAILABLE_IOS(7_0);
- (CGFloat)tableView:(UITableView *)tableView estimatedHeightForFooterInSection:(NSInteger)section NS_AVAILABLE_IOS(7_0);
// 分区的header和footer信息，
- (nullable UIView *)tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section; // custom view for header. will be adjusted to default or specified header height
- (nullable UIView *)tableView:(UITableView *)tableView viewForFooterInSection:(NSInteger)section; // custom view for footer. will be adjusted to default or specified footer height
// 选中的事件
// -tableView:shouldHighlightRowAtIndexPath: 当按下row的时候被执行
// 停止选中的过程会返回 NO， 不会让已选中的失去被选中的状态
- (BOOL)tableView:(UITableView *)tableView shouldHighlightRowAtIndexPath:(NSIndexPath *)indexPath NS_AVAILABLE_IOS(6_0);
- (void)tableView:(UITableView *)tableView didHighlightRowAtIndexPath:(NSIndexPath *)indexPath NS_AVAILABLE_IOS(6_0);
- (void)tableView:(UITableView *)tableView didUnhighlightRowAtIndexPath:(NSIndexPath *)indexPath NS_AVAILABLE_IOS(6_0);
// Called before the user changes the selection. Return a new indexPath, or nil, to change the proposed selection.
- (nullable NSIndexPath *)tableView:(UITableView *)tableView willSelectRowAtIndexPath:(NSIndexPath *)indexPath;
- (nullable NSIndexPath *)tableView:(UITableView *)tableView willDeselectRowAtIndexPath:(NSIndexPath *)indexPath NS_AVAILABLE_IOS(3_0);
// Called after the user changes the selection.
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath;
- (void)tableView:(UITableView *)tableView didDeselectRowAtIndexPath:(NSIndexPath *)indexPath NS_AVAILABLE_IOS(3_0);
// 编辑
// Allows customization of the editingStyle for a particular cell located at 'indexPath'. If not implemented, all editable cells will have UITableViewCellEditingStyleDelete set for them when the table has editing property set to YES.
- (UITableViewCellEditingStyle)tableView:(UITableView *)tableView editingStyleForRowAtIndexPath:(NSIndexPath *)indexPath;
- (nullable NSString *)tableView:(UITableView *)tableView titleForDeleteConfirmationButtonForRowAtIndexPath:(NSIndexPath *)indexPath NS_AVAILABLE_IOS(3_0) __TVOS_PROHIBITED;
- (nullable NSArray<UITableViewRowAction *> *)tableView:(UITableView *)tableView editActionsForRowAtIndexPath:(NSIndexPath *)indexPath NS_AVAILABLE_IOS(8_0) __TVOS_PROHIBITED; // supercedes -tableView:titleForDeleteConfirmationButtonForRowAtIndexPath: if return value is non-nil
// Controls whether the background is indented while editing. If not implemented, the default is YES. This is unrelated to the indentation level below. This method only applies to grouped style table views.
- (BOOL)tableView:(UITableView *)tableView shouldIndentWhileEditingRowAtIndexPath:(NSIndexPath *)indexPath;
// The willBegin/didEnd methods are called whenever the 'editing' property is automatically changed by the table (allowing insert/delete/move). This is done by a swipe activating a single row
- (void)tableView:(UITableView*)tableView willBeginEditingRowAtIndexPath:(NSIndexPath *)indexPath __TVOS_PROHIBITED;
- (void)tableView:(UITableView*)tableView didEndEditingRowAtIndexPath:(NSIndexPath *)indexPath __TVOS_PROHIBITED;
// Moving/reordering
// Allows customization of the target row for a particular row as it is being moved/reordered
- (NSIndexPath *)tableView:(UITableView *)tableView targetIndexPathForMoveFromRowAtIndexPath:(NSIndexPath *)sourceIndexPath toProposedIndexPath:(NSIndexPath *)proposedDestinationIndexPath;
// Indentation
- (NSInteger)tableView:(UITableView *)tableView indentationLevelForRowAtIndexPath:(NSIndexPath *)indexPath; // return 'depth' of row for hierarchies
// Copy/Paste. All three methods must be implemented by the delegate.
- (BOOL)tableView:(UITableView *)tableView shouldShowMenuForRowAtIndexPath:(NSIndexPath *)indexPath NS_AVAILABLE_IOS(5_0);
- (BOOL)tableView:(UITableView *)tableView canPerformAction:(SEL)action forRowAtIndexPath:(NSIndexPath *)indexPath withSender:(nullable id)sender NS_AVAILABLE_IOS(5_0);
- (void)tableView:(UITableView *)tableView performAction:(SEL)action forRowAtIndexPath:(NSIndexPath *)indexPath withSender:(nullable id)sender NS_AVAILABLE_IOS(5_0);
// Focus
- (BOOL)tableView:(UITableView *)tableView canFocusRowAtIndexPath:(NSIndexPath *)indexPath NS_AVAILABLE_IOS(9_0);
- (BOOL)tableView:(UITableView *)tableView shouldUpdateFocusInContext:(UITableViewFocusUpdateContext *)context NS_AVAILABLE_IOS(9_0);
- (void)tableView:(UITableView *)tableView didUpdateFocusInContext:(UITableViewFocusUpdateContext *)context withAnimationCoordinator:(UIFocusAnimationCoordinator *)coordinator NS_AVAILABLE_IOS(9_0);
- (nullable NSIndexPath *)indexPathForPreferredFocusedViewInTableView:(UITableView *)tableView NS_AVAILABLE_IOS(9_0);
UICollectionViewDataSource
Collectionview的使用和Tableview的使用非常类似。常用的数据源配置有如下方法：
@required
//返回每个section中的item的数量
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section;
// 返回的cell必须从以下的方法取得 -dequeueReusableCellWithReuseIdentifier:forIndexPath:
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath;
@optional
//分区的数量
- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView;
// 返回的view必须从以下的方法取得 -dequeueReusableSupplementaryViewOfKind:withReuseIdentifier:forIndexPath:
- (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath;
//返回item是否可以被移动
- (BOOL)collectionView:(UICollectionView *)collectionView canMoveItemAtIndexPath:(NSIndexPath *)indexPath NS_AVAILABLE_IOS(9_0);
//移动item
- (void)collectionView:(UICollectionView *)collectionView moveItemAtIndexPath:(NSIndexPath *)sourceIndexPath toIndexPath:(NSIndexPath*)destinationIndexPath NS_AVAILABLE_IOS(9_0);
UICollectionViewDelegate
// 选中的方法
// 用户touch之后的方法调用顺序:
//
// (touch开始的时候)
// 1. -collectionView:shouldHighlightItemAtIndexPath:
// 2. -collectionView:didHighlightItemAtIndexPath:
//
// (touch离开的时候)
// 3. -collectionView:shouldSelectItemAtIndexPath: or -collectionView:shouldDeselectItemAtIndexPath:
// 4. -collectionView:didSelectItemAtIndexPath: or -collectionView:didDeselectItemAtIndexPath:
// 5. -collectionView:didUnhighlightItemAtIndexPath:
- (BOOL)collectionView:(UICollectionView *)collectionView shouldHighlightItemAtIndexPath:(NSIndexPath *)indexPath;
- (void)collectionView:(UICollectionView *)collectionView didHighlightItemAtIndexPath:(NSIndexPath *)indexPath;
- (void)collectionView:(UICollectionView *)collectionView didUnhighlightItemAtIndexPath:(NSIndexPath *)indexPath;
- (BOOL)collectionView:(UICollectionView *)collectionView shouldSelectItemAtIndexPath:(NSIndexPath *)indexPath;
- (BOOL)collectionView:(UICollectionView *)collectionView shouldDeselectItemAtIndexPath:(NSIndexPath *)indexPath; // called when the user taps on an already-selected item in multi-select mode
- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath;
- (void)collectionView:(UICollectionView *)collectionView didDeselectItemAtIndexPath:(NSIndexPath *)indexPath;
对Tableview和Collectionview的使用主要就是这两个协议，一个负责数据来源，一个负责处理和用户的交互。使用方法也非常类似。
