@interface ...
{
    UIView *disableViewOverlay;
    ...
}

@property(retain) UIView *disableViewOverlay;

@synthesize disableViewOverlay;

...

-(void) disableSearchBar
{
    self.disableViewOverlay = [[UIView alloc]
                           initWithFrame:CGRectMake(0.0f,0.0f,320.0f,44.0f)];
    self.disableViewOverlay.backgroundColor=[UIColor blackColor];
    self.disableViewOverlay.alpha = 0;

    self.disableViewOverlay.alpha = 0;
    [self.view addSubview:self.disableViewOverlay];

    [UIView beginAnimations:@"FadeIn" context:nil];
    [UIView setAnimationDuration:0.5];
    self.disableViewOverlay.alpha = 0.4;
    [UIView commitAnimations];
}

-(void) enableSearchBar
{
    [disableViewOverlay removeFromSuperview];
    [searchBar resignFirstResponder];
}