iPhone keyboard, Done button and resignFirstResponder

I made a small test project with just a UITextField and this code

#import <UIKit/UIKit.h>
@interface TextFieldTestViewController : UIViewController
<UITextFieldDelegate>
{
    UITextField *textField;
}
@property (nonatomic, retain) IBOutlet UITextField *textField;
@end

#import "TextFieldTestViewController.h"
@implementation TextFieldTestViewController
@synthesize textField;

- (void)viewDidLoad
{
    [self.textField setDelegate:self];
    [self.textField setReturnKeyType:UIReturnKeyDone];
    [self.textField addTarget:self
                  action:@selector(textFieldFinished:)
        forControlEvents:UIControlEventEditingDidEndOnExit];
    [super viewDidLoad];
}
- (IBAction)textFieldFinished:(id)sender
{
    // [sender resignFirstResponder];
}

- (void)dealloc {
    [super dealloc];
}
@end

The text field is an unmodified UITextField dragged onto the NIB, with the outlet connected.
After loading the app, clicking in the text field brings up the keyboard. Pressing the “Done” button makes the text field lose focus and animates out the keyboard. Note that the advice around the web is to always use [sender resignFirstResponder] but this works without it.