今天用到UISearchBar，之前網上提供的方法已經不能有效的去除掉它的背景色了，修改背景色方法如下：

mySearchBar.backgroundColor = RGBACOLOR(249,249,249,1);
    mySearchBar.backgroundImage = [self imageWithColor:[UIColor clearColor] size:mySearchBar.bounds.size];
 
//取消searchbar背景色
- (UIImage *)imageWithColor:(UIColor *)color size:(CGSize)size
{
    CGRect rect = CGRectMake(0, 0, size.width, size.height);
    UIGraphicsBeginImageContext(rect.size);
    CGContextRef context = UIGraphicsGetCurrentContext();
     
    CGContextSetFillColorWithColor(context, [color CGColor]);
    CGContextFillRect(context, rect);
     
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
     
    return image;
}