SearchBar使用设置的一些属性

        //设置searchBar Placeholder的字体颜色

//        [[UILabel appearanceWhenContainedIn:[_searchBar class], nil] setTextColor:[UIColor grayTextColor]];

        // Get the instance of the UITextField of the search bar

        UITextField *searchField = [_searchBar valueForKey:@"_searchField"];

        // Change search bar text color

        searchField.textColor = [UIColor whiteColor];

        // Change the search bar placeholder text color

        [searchField setValue:[UIColor grayTextColor] forKeyPath:@"_placeholderLabel.textColor"];

        

        if(__gSystemVersion >= 7){

            _searchBar.searchBarStyle = UISearchBarStyleDefault;

        }

    searchBar.backgroundColor = bgColor;

    UIView *topView = searchBar;

    if (__gSystemVersion >= 7.0) {

        topView = [[searchBar subviews] objectAtIndex:0];

        searchBar.barTintColor = [UIColor clearColor];

    }

    //隐藏searchBar的默认背景

    for (UIView *subView in topView.subviews) {

        if ([subView isKindOfClass:NSClassFromString(@"UISearchBarBackground")]) {

            [subView removeFromSuperview];

            break;

        }

    }