去掉navigationController的底部黑线

</pre><pre name="code" class="objc"><span style="font-family: Arial, Helvetica, sans-serif;">if ([self.navigationController.navigationBar respondsToSelector:@selector( setBackgroundImage:forBarMetrics:)]){</span>

        NSArray *list=self.navigationController.navigationBar.subviews;        for (id obj in list) {            if ([obj isKindOfClass:[UIImageView class]]) {                UIImageView *imageView=(UIImageView *)obj;                NSArray *list2=imageView.subviews;                for (id obj2 in list2) {                    if ([obj2 isKindOfClass:[UIImageView class]]) {                        UIImageView *imageView2=(UIImageView *)obj2;                        imageView2.hidden=YES;                    }                }            }        }    }