修改UISearchBar的背景色

 // 创建搜索框

        UISearchBar*searchBar = [[UISearchBaralloc]initWithFrame:CGRectMake(10,Is_iPhoneX_Top+22,KWIDTH-60,32)];

        searchBar.placeholder=@"想知道点什么呢";

        searchBar.delegate=self;

        searchBar.layer.cornerRadius=16;

        searchBar.layer.masksToBounds=YES;

        searchBar.barTintColor=kColor(238,238,238);

        //[searchBar.layer setBorderWidth:8];

        //[searchBar.layer setBorderColor:[UIColor whiteColor].CGColor];

        //用颜色图片来替换背景图片

        [searchBarsetSearchFieldBackgroundImage:[self imageFromColor:kColor(238, 238, 238) withSize:CGSizeMake(KWIDTH-60, 36)] forState:UIControlStateNormal]; //输入背景框

        [selfaddSubview:searchBar];

// 将UIColor转换成图片

- (nullableUIImage*)imageFromColor: (nonnullUIColor*)color withSize:(CGSize)size {

    CGRectrect =CGRectMake(0,0, size.width, size.height);

    UIGraphicsBeginImageContextWithOptions(rect.size, NO, [UIScreen mainScreen].scale);

    CGContextRef context = UIGraphicsGetCurrentContext();

    CGContextSetFillColorWithColor(context,color.CGColor);

    CGContextFillRect(context, rect);

    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();

    UIGraphicsEndImageContext();

    returnimage;

}