Datasets:

Vikhrmodels

/

programming_books_eng

like 1

Follow

Vikhr models 146

numberOfRowsInSection:(NSInteger)section

{

#warning Incomplete method implementation.

// Return the number of rows in the section.

return 0;

}

You want to return the number of list items you have. Fortunately, NSArray has a handy method called

count that returns the number of items in the array, so the number of rows is [self.toDoItems count].

3.

Change the tableView:numberOfRowsInSection: data source method to return the appropriate

number of rows.

- (NSInteger)tableView:(UITableView *)tableView

numberOfRowsInSection:(NSInteger)section

{

}

// Return the number of rows in the section.

return [self.toDoItems count];

The last method, tableView:cellForRowAtIndexPath:, asks for a cell to display for a given row. Up until

now, you’ve been working with code only, but the cell to display for a row is very much part of your interface.

Fortunately, Xcode makes it easy to design custom cells in Interface Builder. The first task is to design your cell

and to tell the table view that instead of using static content, it’s going to be using prototype cells with dynamic

content.

To configure your table view

1. Open your storyboard.

2013-10-22 | Copyright © 2013 Apple Inc. All Rights Reserved.

99

Tutorial: Add Data

Display the Data

2.

Select the table view in the outline.

3. With the table view selected, open the Attributes inspector

in the utility area.

4.

In the Attributes inspector, change the table view’s Content attribute from Static Cells to Dynamic

Prototypes.

Interface Builder takes the static cells you configured and converts them all into prototypes. Prototype cells,

as the name implies, are cells that are configured with text styles, colors, images, or other attributes as you

want them to be displayed but that get their data from the data source at runtime. The data source loads a

prototype cell for each row and then configures that cell to display the data for the row.

To load the correct cell, the data source needs to know what it’s called, and that name must also be configured

in the storyboard.

While you’re setting the prototype cell name, you’ll also configure another property—the cell selection style,

which determines a cell’s appearance when a user taps it. Set the cell selection style to None so that the cell

won’t be highlighted when a user taps it. This is the behavior you want your cells to have when a user taps an

item in the to-do list to mark it as completed or uncompleted—a feature you’ll implement later in this tutorial.

To configure the prototype cell

1.

2.

3.

Select the first table view cell in your table.

In the Attributes inspector, locate the Identifier field and type ListPrototypeCell.

In the Attributes inspector, locate the Selection field and choose None.

You could also change the font or other attributes of the prototype cell. The basic configuration is easy to work

with, so you’ll keep that.

The next step is to teach your data source how to configure the cell for a given row by implementing

tableView:cellForRowAtIndexPath:. This data source method is called by the table view when it wants

to display a given row. For table views with a small number of rows, all rows may be onscreen at once, so this

method gets called for each row in your table. But table views with a large number of rows display only a small

fraction of their total items at a given time. It’s most efficient for table views to only ask for the cell for rows

that are being displayed, and that’s what tableView:cellForRowAtIndexPath: allows the table view to

do.

For any given row in the table, fetch the corresponding entry in the toDoItems array and then set the cell’s