iOS 6/7 UISearchBar的背景色设置

在iOS7中，UISearchBar的子视图变成一个UIView，所以原来的方法不管用了，但是看了一下文档，在iOS7中新增了一个barTintColor的属性，我们可以设置barTintColor为clearColor

float version = [[[UIDevice currentDevice] systemVersion] floatValue];    if ([ searchBar respondsToSelector : @selector (barTintColor)]) {        float  iosversion7_1 = 7.1 ;        if(version >= iosversion7_1)        {            //iOS7.1            [[[[searchBar.subviews objectAtIndex : 0 ] subviews] objectAtIndex:0] removeFromSuperview];            [ searchBar setBackgroundColor:[ UIColor clearColor]];        }        else        {            //iOS7.0            [ searchBar setBarTintColor:[UIColor clearColor]];            [ searchBar setBackgroundColor:[UIColor clearColor]];        }    }    else    {        //iOS7.0 以下        [[searchBar.subviews objectAtIndex:0] removeFromSuperview ];        [searchBar setBackgroundColor:[UIColor clearColor]];    }