- (void)keyboardWillShow:(NSNotification *)notification {
  if(nil != self.view.window){
    CGRect appFrame = [[UIScreen mainScreen] applicationFrame];
    CGRect keyboardBounds = [[[notification userInfo] valueForKey:UIKeyboardBoundsUserInfoKey] CGRectValue];
    CGRect searchBounds = [self.searchBar bounds];
    CGFloat height = CGRectGetHeight(appFrame) - CGRectGetHeight(keyboardBounds) - CGRectGetHeight(searchBounds);
    CGRect visibleBounds = CGRectMake(CGRectGetMinX(appFrame), 
                                      CGRectGetMinY(appFrame) + CGRectGetHeight(searchBounds),
                                      CGRectGetWidth(appFrame), 
                                      height);
    self.overlay.frame = visibleBounds;
  }
}