Since iOS 7 all the subview of UISearchBar are one level deeper. This should work:
for (UIView *subView in searchBar.subviews) {
for (UIView *secondLevelSubview in subView.subviews) {
if ([view isKindOfClass:[UIButton class]]) {
[(UIButton *)view setEnabled:YES];
}
}
Still hacky and can easily break in the next iOS version.