取消iOS10和iOS9以下導航欄黑線

if ([self.navigationController.navigationBar respondsToSelector:@selector( setBackgroundImage:forBarMetrics:)])
    {

        NSArray *list=self.navigationController.navigationBar.subviews;

        for (id obj in list)
        {

            if ([UIDevice currentDevice].systemVersion.floatValue >= )
            {//10.0的系統字段不一樣
                UIView *view = (UIView*)obj;
                for (id obj2 in view.subviews) {

                    if ([obj2 isKindOfClass:[UIImageView class]])
                    {

                        UIImageView *image =  (UIImageView*)obj2;
                        image.hidden = YES;
                    }  
                }
            }
            else
            {
                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;
                        }
                    }
                }
            }

        }
    }