去掉导航栏下 细线

 1     //去除bar下方 线
 2     if ([self.navigationController.navigationBar respondsToSelector:@selector( setBackgroundImage:forBarMetrics:)]){
 3         NSArray *list=self.navigationController.navigationBar.subviews;
 4         for (id obj in list) {
 5             if ([obj isKindOfClass:[UIImageView class]]) {
 6                 UIImageView *imageView=(UIImageView *)obj;
 7                 NSArray *list2=imageView.subviews;
 8                 for (id obj2 in list2) {
 9                     if ([obj2 isKindOfClass:[UIImageView class]]) {
10                         UIImageView *imageView2=(UIImageView *)obj2;
11                         imageView2.hidden=YES;
12                     }
13                 }
14             }
15         }
16     }