iPhone SDK dismiss the keyboard

Set the delegate on the text field that will bring up the keyboard. Add the following selector to the object that you set to be the delegate.

The controller's interface code
#import 
@interface MyViewController : UIViewController  {
 IBOutlet UITextField *textField;
}
@property (nonatomic, retain) UITextField *textField;
@end
And the controller's implementation code
#import "MyViewController.h" 
@implementation MyViewController 
@synthesize textField;
-(BOOL)textFieldShouldReturn:(UITextField *)theTextField {
 if (theTextField == textField) {
  [textField resignFirstResponder];
 }
 return YES;
}
@end