矩形的UISearchBar

for (UIView *searchBarSubview in [self.searchBar subviews]) {
        if ([searchBarSubview conformsToProtocol:@protocol(UITextInputTraits)]) {
            @try {
                [(UITextField *)searchBarSubview setBorderStyle:UITextBorderStyleRoundedRect];
            }
            @catch (NSException * e) {
                // ignore exception
            }
        }
    }