Class

UITableView

A view that presents data using rows arranged in a single column.

Overview

A table view displays a list of items in a single column. UITableView is a subclass of UIScrollView, which allows users to scroll through the table, although UITableView allows vertical scrolling only. The cells comprising the individual items of the table are UITableViewCell objects; UITableView uses these objects to draw the visible rows of the table. Cells have content—titles and images—and can have, near the right edge, accessory views. Standard accessory views are disclosure indicators or detail disclosure buttons; the former leads to the next level in a data hierarchy and the latter leads to a detailed view of a selected item. Accessory views can also be framework controls, such as switches and sliders, or can be custom views. Table views can enter an editing mode where users can insert, delete, and reorder rows of the table.

A table view is made up of zero or more sections, each with its own rows. Sections are identified by their index number within the table view, and rows are identified by their index number within a section. Any section can optionally be preceded by a section header, and optionally be followed by a section footer.

Table views can have one of two styles, UITableViewStylePlain and UITableViewStyleGrouped. When you create a UITableView instance you must specify a table style, and this style cannot be changed. In the plain style, section headers and footers float above the content if the part of a complete section is visible. A table view can have an index that appears as a bar on the right hand side of the table (for example, "A" through "Z"). You can touch a particular label to jump to the target section. The grouped style of table view provides a default background color and a default background view for all cells. The background view provides a visual grouping for all cells in a particular section. For example, one group could be a person's name and title, another group for phone numbers that the person uses, and another group for email accounts and so on. See the Settings application for examples of grouped tables. Table views in the grouped style cannot have an index.

Many methods of UITableView take NSIndexPath objects as parameters and return values. UITableView declares a category on NSIndexPath that enables you to get the represented row index (row property) and section index (section property), and to construct an index path from a given row index and section index (indexPathForRow:inSection: method). Especially in table views with multiple sections, you must evaluate the section index before identifying a row by its index number.

A UITableView object must have an object that acts as a data source and an object that acts as a delegate; typically these objects are either the application delegate or, more frequently, a custom UITableViewController object. The data source must adopt the UITableViewDataSource protocol and the delegate must adopt the UITableViewDelegate protocol. The data source provides information that UITableView needs to construct tables and manages the data model when rows of a table are inserted, deleted, or reordered. The delegate manages table row configuration and selection, row reordering, highlighting, accessory views, and editing operations.

When sent a setEditing:animated: message (with a first parameter of YES), the table view enters into editing mode where it shows the editing or reordering controls of each visible row, depending on the editingStyle of each associated UITableViewCell. Clicking on the insertion or deletion control causes the data source to receive a tableView:commitEditingStyle:forRowAtIndexPath: message. You commit a deletion or insertion by calling deleteRowsAtIndexPaths:withRowAnimation: or insertRowsAtIndexPaths:withRowAnimation:, as appropriate. Also in editing mode, if a table-view cell has its showsReorderControl property set to YES, the data source receives a tableView:moveRowAtIndexPath:toIndexPath: message. The data source can selectively remove the reordering control for cells by implementing tableView:canMoveRowAtIndexPath:.

UITableView caches table-view cells for visible rows. You can create custom UITableViewCell objects with content or behavioral characteristics that are different than the default cells; A Closer Look at Table View Cells explains how.

UITableView overrides the layoutSubviews method of UIView so that it calls reloadData only when you create a new instance of UITableView or when you assign a new data source. Reloading the table view clears current state, including the current selection. However, if you explicitly call reloadData, it clears this state and any subsequent direct or indirect call to layoutSubviews does not trigger a reload.

State Preservation

If you assign a value to a table view’s restorationIdentifier property, it attempts to preserve the currently selected rows and the first visible row. The table’s data source may adopt the UIDataSourceModelAssociation protocol, which provides a way to identify a row’s contents independent of that row’s position in the table. If the table’s data source adopts the UIDataSourceModelAssociation protocol, the data source will be consulted when saving state to convert the index paths for the top visible row and any selected cells to identifiers. During restoration, the data source will be consulted to convert those identifiers back to index paths and reestablish the top visible row, and reselect the cells. If the table’s data source does not implement the UIDataSourceModelAssociation protocol, the scroll position will be saved and restored directly, as will the index paths for selected cells.

For more information about how state preservation and restoration works, see App Programming Guide for iOS.

For more information about appearance and behavior configuration, see Table Views.

Topics

Initializing a UITableView Object

initWithFrame:style:

Initializes and returns a table view object having the given frame and style.

Providing the Table View Data

dataSource

The object that acts as the data source of the table view.

UITableViewDataSource

The UITableViewDataSource protocol is adopted by an object that mediates the application’™s data model for a UITableView object. The data source provides the table-view object with the information it needs to construct and modify a table view.

UITableViewDataSourcePrefetching

A protocol that provides advance warning of the data requirements for a table view, allowing the triggers of asynchronous data load operations.

Customizing the Table View Behavior

delegate

The object that acts as the delegate of the table view.

UITableViewDelegate

The delegate of a UITableView object must adopt the UITableViewDelegate protocol. Optional methods of the protocol allow the delegate to manage selections, configure section headings and footers, help to delete and reorder cells, and perform other actions.

Configuring a Table View

style

Returns the style of the table view.

numberOfRowsInSection:

Returns the number of rows (table cells) in a specified section.

numberOfSections

The number of sections in the table view.

rowHeight

The height of each row (that is, table cell) in the table view.

separatorStyle

The style for table cells used as separators.

separatorColor

The color of separator rows in the table view.

separatorEffect

The effect applied to table separators.

backgroundView

The background view of the table view.

separatorInset

Specifies the default inset of cell separators.

separatorInsetReference

An indicator of how the separator inset value should be interpreted.

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UITableViewSeparatorInsetReference

Constants indicating how to interpret the separator inset value of a table view.

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cellLayoutMarginsFollowReadableWidth

A Boolean value that indicates whether the cell margins are derived from the width of the readable content guide.

Creating Table View Cells

registerNib:forCellReuseIdentifier:

Registers a nib object containing a cell with the table view under a specified identifier.

registerClass:forCellReuseIdentifier:

Registers a class for use in creating new table cells.

dequeueReusableCellWithIdentifier:forIndexPath:

Returns a reusable table-view cell object for the specified reuse identifier and adds it to the table.

dequeueReusableCellWithIdentifier:

Returns a reusable table-view cell object located by its identifier.

Accessing Header and Footer Views

registerNib:forHeaderFooterViewReuseIdentifier:

Registers a nib object containing a header or footer with the table view under a specified identifier.

registerClass:forHeaderFooterViewReuseIdentifier:

Registers a class for use in creating new table header or footer views.

dequeueReusableHeaderFooterViewWithIdentifier:

Returns a reusable header or footer view located by its identifier.

tableHeaderView

Returns an accessory view that is displayed above the table.

tableFooterView

Returns an accessory view that is displayed below the table.

sectionHeaderHeight

The height of section headers in the table view.

sectionFooterHeight

The height of section footers in the table view.

headerViewForSection:

Returns the header view associated with the specified section.

footerViewForSection:

Returns the footer view associated with the specified section.

Accessing Cells and Sections

cellForRowAtIndexPath:

Returns the table cell at the specified index path.

indexPathForCell:

Returns an index path representing the row and section of a given table-view cell.

indexPathForRowAtPoint:

Returns an index path identifying the row and section at the given point.

indexPathsForRowsInRect:

An array of index paths each representing a row enclosed by a given rectangle.

visibleCells

The table cells that are visible in the table view.

indexPathsForVisibleRows

An array of index paths each identifying a visible row in the table view.

Estimating Element Heights

estimatedRowHeight

The estimated height of rows in the table view.

estimatedSectionHeaderHeight

The estimated height of section headers in the table view.

estimatedSectionFooterHeight

The estimated height of section footers in the table view.

Scrolling the Table View

scrollToRowAtIndexPath:atScrollPosition:animated:

Scrolls through the table view until a row identified by index path is at a particular location on the screen.

scrollToNearestSelectedRowAtScrollPosition:animated:

Scrolls the table view so that the selected row nearest to a specified position in the table view is at that position.

Managing Selections

indexPathForSelectedRow

An index path identifying the row and section of the selected row.

indexPathsForSelectedRows

The index paths representing the selected rows.

selectRowAtIndexPath:animated:scrollPosition:

Selects a row in the table view identified by index path, optionally scrolling the row to a location in the table view.

deselectRowAtIndexPath:animated:

Deselects a given row identified by index path, with an option to animate the deselection.

allowsSelection

A Boolean value that determines whether users can select a row.

allowsMultipleSelection

A Boolean value that determines whether users can select more than one row outside of editing mode.

allowsSelectionDuringEditing

A Boolean value that determines whether users can select cells while the table view is in editing mode.

allowsMultipleSelectionDuringEditing

A Boolean value that controls whether users can select more than one cell simultaneously in editing mode.

Inserting, Deleting, and Moving Rows and Sections

insertRowsAtIndexPaths:withRowAnimation:

Inserts rows in the table view at the locations identified by an array of index paths, with an option to animate the insertion.

deleteRowsAtIndexPaths:withRowAnimation:

Deletes the rows specified by an array of index paths, with an option to animate the deletion.

moveRowAtIndexPath:toIndexPath:

Moves the row at a specified location to a destination location.

insertSections:withRowAnimation:

Inserts one or more sections in the table view, with an option to animate the insertion.

deleteSections:withRowAnimation:

Deletes one or more sections in the table view, with an option to animate the deletion.

moveSection:toSection:

Moves a section to a new location in the table view.

performBatchUpdates:completion:

Animates multiple insert, delete, reload, and move operations as a group.

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beginUpdates

Begins a series of method calls that insert, delete, or select rows and sections of the table view.

endUpdates

Concludes a series of method calls that insert, delete, select, or reload rows and sections of the table view.

Managing Drag Interactions

dragDelegate

The delegate object that manages the dragging of items from the table view.

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UITableViewDragDelegate

The interface for initiating drags from a table view.

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hasActiveDrag

A Boolean value indicating whether rows were lifted from the table view and have not yet been dropped.

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dragInteractionEnabled

A Boolean value indicating whether the table view supports drags and drops between apps.

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Managing Drop Interactions

dropDelegate

The delegate object that manages the dropping of content into the table view.

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UITableViewDropDelegate

The interface for handling drops in a table view.

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Managing the Editing of Table Cells

editing

A Boolean value that determines whether the table view is in editing mode.

setEditing:animated:

Toggles the table view into and out of editing mode.

Reloading the Table View

hasUncommittedUpdates

A Boolean value indicating whether the table view contains drop placeholders or is reordering its rows as part of handling a drop.

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reloadData

Reloads the rows and sections of the table view.

reloadRowsAtIndexPaths:withRowAnimation:

Reloads the specified rows using an animation effect.

reloadSections:withRowAnimation:

Reloads the specified sections using a given animation effect.

reloadSectionIndexTitles

Reloads the items in the index bar along the right side of the table view.

Accessing Drawing Areas of the Table View

rectForSection:

Returns the drawing area for a specified section of the table view.

rectForRowAtIndexPath:

Returns the drawing area for a row identified by index path.

rectForFooterInSection:

Returns the drawing area for the footer of the specified section.

rectForHeaderInSection:

Returns the drawing area for the header of the specified section.

Prefetching Data

If your table view relies on an expensive data loading process, you can improve your user experience by prefetching data before it is needed for display. Assign an object that conforms to the UITableViewDataSourcePrefetching protocol to the prefetchDataSource property to receive notifications of when to prefetch data for cells.

prefetchDataSource

The object that acts as the prefetching data source for the table view, receiving notifications of upcoming cell data requirements.

Configuring the Table Index

sectionIndexMinimumDisplayRowCount

The number of table rows at which to display the index list on the right edge of the table.

sectionIndexColor

The color to use for the table view’s index text.

sectionIndexBackgroundColor

The color to use for the background of the table view’s section index while not being touched.

sectionIndexTrackingBackgroundColor

The color to use for the table view’s index background area.

Managing Focus

remembersLastFocusedIndexPath

A Boolean value that indicates whether the table view should automatically return the focus to the cell at the last focused index path.

Constants

UITableViewStyle

The style of the table view.

UITableViewScrollPosition

The position in the table view (top, middle, bottom) to which a given row is scrolled.

UITableViewRowAnimation

The type of animation when rows are inserted or deleted.

Section Index Icons

Requests icon to be shown in the section index of a table view.

Default Dimension

The default value for a given dimension.

Notifications

UITableViewSelectionDidChangeNotification

Posted when the selected row in the posting table view changes.

Instance Properties

Relationships

Inherits From

See Also

View

UITableViewController

A controller object that manages a table view.

UITableViewFocusUpdateContext

A context object that provides information relevant to a specific focus update from one view to another.

UILocalizedIndexedCollation

An object that provides ways to organize, sort, and localize the data for a table view that has a section index.

Beta Software

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