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undeclared identifier XYZToDoItem.” This means that the compiler doesn’t know about your XYZToDoItem
when it’s compiling XYZToDoListViewController. Compilers are very particular and need to be told
explicitly what to pay attention to.
To tell the compiler to pay attention to your custom list item class
1.
Find the #import "XYZToDoListViewController.h" line near the top of the
XYZToDoListViewController.m file.
2. Add the following line immediately below it:
#import "XYZToDoItem.h"
Checkpoint: Build your project by choosing Product > Build. It should build without errors.
2013-10-22 | Copyright © 2013 Apple Inc. All Rights Reserved.
97
Tutorial: Add Data
Display the Data
Display the Data
At this point, your table view has a mutable array that’s prepopulated with some sample to-do items. Now you
need to display the data in the table view.
You’ll do this by making XYZToDoListViewController a data source of the table view. To make something
a data source of the table view, it needs to implement the UITableViewDataSource protocol. It turns out
that the methods you need to implement are exactly the ones you commented out in the second tutorial. To
have a functioning table view requires three methods. The first of these is numberOfSectionsInTableView:,
which tells the table view how many sections to display. For this app, you want the table view to display a
single section, so the implementation is straightforward.
To display a section in your table
1.
2.
In the project navigator, select XYZToDoListViewController.m.
If you commented out the table view data source methods in the second tutorial, remove those comment
markers now.
3.
Find the section of the template implementation that looks like this.
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
#warning Potentially incomplete method implementation.
// Return the number of sections.
return 0;
}
You want a single section, so you want to remove the warning line and change the return value from 0
to 1.
4. Change the numberOfSectionsInTableView: data source method to return a single section, like this:
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
}
// Return the number of sections.
return 1;
2013-10-22 | Copyright © 2013 Apple Inc. All Rights Reserved.
98
Tutorial: Add Data
Display the Data
The next method, tableView:numberOfRowsInSection:, tells the table view how many rows to display
in a given section. You have a single section in your table, and each to-do item should have its own row in the
table view. That means that the number of rows should be the number of XYZToDoItem objects in your
toDoItems array.
To return the number of rows in your table
1.
2.
In the project navigator, select XYZToDoListViewController.m.
Find the section of the template implementation that looks like this:
- (NSInteger)tableView:(UITableView *)tableView