From iPhone Development Wiki

UITableViewCell is view that displays a cell (row) in a UITableView.

Using text field in table cells

Signature @property(readonly, retain, nonatomic) UITextField* editableTextField;
Available in 3.0 –

You can associate a text field to a table view cell by initializing it with

cell = [[[UITableViewCell alloc] initWithStyle:1000 reuseIdentifier:@"..."] autorelease];

The properties of the extra text field can be edited via the editableTextField property.

Note that this text field is not very "smart". The table view won't scroll to a suitable position when the keyboard appears, for example.