Use the appearance proxy:
id barButtonAppearanceInSearchBar = [UIBarButtonItem appearanceWhenContainedIn:[UISearchBar class], nil];
[barButtonAppearanceInSearchBar setBackgroundImage:grayBackgroundImage forState:UIControlStateNormal barMetrics:UIBarMetricsDefault];
[barButtonAppearanceInSearchBar setTitleTextAttributes:@{
NSFontAttributeName : [UIFont fontWithName:@"HelveticaNeue-CondensedBold" size:20],
NSForegroundColorAttributeName : [UIColor blackColor]
} forState:UIControlStateNormal];
[barButtonAppearanceInSearchBar setTitle:@"X"];