UISearchBar 设置背景透明色

简单记录一下，，，

  UIImage* searchBarBg = [self GetImageWithColor:[UIColor clearColor] andHeight:20.0f];
    [_searchBar setBackgroundImage:searchBarBg];
    [_searchBar setBackgroundColor:[UIColor clearColor]];
    [_searchBar setSearchFieldBackgroundImage:searchBarBg forState:UIControlStateNormal];

- (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;
}