What are required delegates and data sources for Table View?

UITableViewDelegate

Serving as a table's delegate means you provide answers to requests about the layout of the table and about actions the user performs on the tableview. Layout methods include the tableview asking about the height of rows, headers, and footers, what the buttons should look like, etc. Action methods include the user selecting a row and beginning and ending the editing of a row.

UITableViewDatasource

Serving as a table's datasource means you provide data for the sections and rows of a table and you act on messages that change a table's data. The datasource is asked for the data for a cell when the table is drawn, is told that the user has asked to delete a row, and is told the new value of a row that the user has edited.

Required Delegates:

// this represents the display and behaviour of the cells.

@protocol UITableViewDelegate<NSObject, UIScrollViewDelegate>

@optional

// Display customization

- (void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath;

// Variable height support

- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath;

- (CGFloat)tableView:(UITableView *)tableView heightForHeaderInSection:(NSInteger)section;

- (CGFloat)tableView:(UITableView *)tableView heightForFooterInSection:(NSInteger)section;

// Section header & footer information. Views are preferred over title should you decide to provide both

- (UIView *)tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section;   // custom view for header. will be adjusted to default or specified header height

- (UIView *)tableView:(UITableView *)tableView viewForFooterInSection:(NSInteger)section;   // custom view for footer. will be adjusted to default or specified footer height

// Accessories (disclosures). 

- (UITableViewCellAccessoryType)tableView:(UITableView *)tableViewaccessoryTypeForRowWithIndexPath:(NSIndexPath *)indexPath __OSX_AVAILABLE_BUT_DEPRECATED(__MAC_NA,__MAC_NA,__IPHONE_2_0,__IPHONE_3_0);

- (void)tableView:(UITableView *)tableViewaccessoryButtonTappedForRowWithIndexPath:(NSIndexPath *)indexPath;

// Selection

// Called before the user changes the selection. Return a new indexPath, or nil, to change the proposed selection.

- (NSIndexPath *)tableView:(UITableView *)tableViewwillSelectRowAtIndexPath:(NSIndexPath *)indexPath;

- (NSIndexPath *)tableView:(UITableView *)tableViewwillDeselectRowAtIndexPath:(NSIndexPath *)indexPath __OSX_AVAILABLE_STARTING(__MAC_NA,__IPHONE_3_0);

// Called after the user changes the selection.

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath;

- (void)tableView:(UITableView *)tableView didDeselectRowAtIndexPath:(NSIndexPath *)indexPath __OSX_AVAILABLE_STARTING(__MAC_NA,__IPHONE_3_0);

// Editing

// 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 *)tableVieweditingStyleForRowAtIndexPath:(NSIndexPath *)indexPath;

- (NSString *)tableView:(UITableView *)tableViewtitleForDeleteConfirmationButtonForRowAtIndexPath:(NSIndexPath*)indexPath __OSX_AVAILABLE_STARTING(__MAC_NA,__IPHONE_3_0);

// 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 *)tableViewshouldIndentWhileEditingRowAtIndexPath:(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;

- (void)tableView:(UITableView*)tableView didEndEditingRowAtIndexPath:(NSIndexPath *)indexPath;

// Moving/reordering

// Allows customization of the target row for a particular row as it is being moved/reordered

- (NSIndexPath *)tableView:(UITableView *)tableViewtargetIndexPathForMoveFromRowAtIndexPath:(NSIndexPath*)sourceIndexPath toProposedIndexPath:(NSIndexPath*)proposedDestinationIndexPath;               

// Indentation

- (NSInteger)tableView:(UITableView *)tableViewindentationLevelForRowAtIndexPath:(NSIndexPath *)indexPath; // return 'depth' of row for hierarchies

@end

Required Datasources:


// this protocol represents the data model object. as such, it supplies no information about appearance (including the cells)

@protocol UITableViewDataSource<NSObject>

@required

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section;

// Row display. Implementers should *always* try to reuse cells by setting each cell's reuseIdentifier and querying for available reusable cells with dequeueReusableCellWithIdentifier:

// Cell gets various attributes set automatically based on table (separators) and data source (accessory views, editing controls)

- (UITableViewCell *)tableView:(UITableView *)tableViewcellForRowAtIndexPath:(NSIndexPath *)indexPath;

@optional

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView;              // Default is 1 if not implemented

- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section;    // fixed font style. use custom view (UILabel) if you want something different

- (NSString *)tableView:(UITableView *)tableView titleForFooterInSection:(NSInteger)section;

// Editing

// Individual rows can opt out of having the -editing property set for them. If not implemented, all rows are assumed to be editable.

- (BOOL)tableView:(UITableView *)tableView canEditRowAtIndexPath:(NSIndexPath *)indexPath;

// Moving/reordering

// Allows the reorder accessory view to optionally be shown for a particular row. By default, the reorder control will be shown only if the datasource implements -tableView:moveRowAtIndexPath:toIndexPath:

- (BOOL)tableView:(UITableView *)tableView canMoveRowAtIndexPath:(NSIndexPath *)indexPath;

// Index

- (NSArray *)sectionIndexTitlesForTableView:(UITableView *)tableView;                                                    // return list of section titles to display in section index view (e.g. "ABCD...Z#")

- (NSInteger)tableView:(UITableView *)tableView sectionForSectionIndexTitle:(NSString *)title atIndex:(NSInteger)index;  // tell table which section corresponds to section title/index (e.g. "B",1))

// Data manipulation - insert and delete support

// After a row has the minus or plus button invoked (based on the UITableViewCellEditingStyle for the cell), the dataSource must commit the change

- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath*)indexPath;

// Data manipulation - reorder / moving support

- (void)tableView:(UITableView *)tableView moveRowAtIndexPath:(NSIndexPath *)sourceIndexPath toIndexPath:(NSIndexPath*)destinationIndexPath;
@end