UISearchBar设置barTintColor“无效”

设置UISearchBar背景色，就调用barTintColor，发现无效，可是查了官方文档和别人的blog,都说这个属性就可以。后来又读到以下一段文字：

UISearchBar是由两个subView组成的，一个是UISearchBarBackGround,另一个是UITextField.

就用于Reveal工具调试，才找到原因，原来是UITextField把UISearchBarBackGround盖住了。示例代码如下：
ViewController.m

    //自定义导航栏
    CGFloat navViewH = 44;
    UIView *navView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, kScreenWidth, 44)];
    //    navView.backgroundColor = [UIColor blueColor];
    //自定义导航栏左侧按钮
    CGFloat      leftImageViewX = 10;
    CGFloat      leftImageViewW = 15;
    CGFloat      leftImageViewH = 25;
    CGFloat      leftImageViewY = (navViewH - leftImageViewH)/2;
    UIImageView *leftImageView = [[UIImageView alloc] initWithFrame:CGRectMake(leftImageViewX, leftImageViewY, leftImageViewW, leftImageViewH)];
    leftImageView.image = [UIImage imageNamed:@"8-2"];
    [navView addSubview:leftImageView];
    //自定义中间搜索框
    CGFloat     searchBarW = kScreenWidth * 3/4;
    CGFloat     searchBorder = 20;
    CGFloat     searchBarH = 30;
    CGFloat     searchBarY = (navViewH - searchBarH)/2;
    UISearchBar *searchBar = [[UISearchBar alloc] initWithFrame:CGRectMake(CGRectGetMaxX(leftImageView.frame) + searchBorder, searchBarY, searchBarW, searchBarH)];
    [navView addSubview:searchBar];
    searchBar.layer.cornerRadius = 15;
    searchBar.clipsToBounds = YES;
    searchBar.placeholder = @"请输入目的地、地标或民宿名称";
    searchBar.barTintColor = [UIColor yellowColor];
    //去掉上下边框黑色
    //    searchBar.backgroundImage = [[UIImage alloc] init];
    self.navigationController.navigationBar.items.lastObject.titleView = navView;

从图上可以看出，是SearchFeild遮住了SearchBackgroud

498970DF-5465-4535-A41A-B69F4017128A.png

知道了原因就好办了，用searchBar自带方法，解决方案如下：

 [searchBar setSearchFieldBackgroundImage:[UIImage createImageWithColor:[UIColor greenColor]] forState:UIControlStateNormal];

Reveal的截图如下：

8E4FCB3B-CB37-4974-84D1-E9ED0FEA327C.png