Hiding the keyboard at the touch of a button?

I am creating an application for the iPhone, which I will show below.

At the end of the screen, I have a text box. I added a delegate for the same. Since this is a numeric pad, I added the button separately so that when the button is pressed, the keyboard is hidden.

Below is the code:

.h

@interface SearchViewController : UIViewController<UITextFieldDelegate>

@property (retain, nonatomic) IBOutlet UITextField *textField006;
@property (retain, nonatomic) IBOutlet UIButton *doneButton;
- (IBAction)doneAction:(id)sender;

.m

- (BOOL)textFieldShouldReturn:(UITextField *)textField
{
    NSLog(@"textFieldShouldReturn");
    return YES;
}

- (void)textFieldDidBeginEditing:(UITextField *)textField
{
    NSLog(@"textFieldDidBeginEditing");
    // Ensure the relevant text field is visible
    CGAffineTransform translation = CGAffineTransformIdentity;
    CGRect screenBound = [[UIScreen mainScreen] bounds];
    CGSize screenSize = screenBound.size;
    CGFloat screenHeight = screenSize.height;

    if (screenHeight==480 || screenHeight==568) {
            translation = CGAffineTransformMakeTranslation(0, -120);
        doneButton.hidden = NO;
        NSLog(@"line 3");
        [UIView beginAnimations:nil context:nil];
        self.view.transform = translation;
        [UIView commitAnimations];
    }
}

- (IBAction)doneAction:(id)sender {
    doneButton.hidden = NO;    
    doneButton.hidden = YES;
    [textField006 resignFirstResponder];
    [UIView beginAnimations:nil context:nil];
    self.view.transform = CGAffineTransformIdentity;
    [UIView commitAnimations];
    [self.textField006 resignFirstResponder];

}

Why is the keyboard not hiding? How can I hide this?

Keyboard == Decimal Panel Return Key → Go Auto-enable Return key = Ticked