之前项目要求隐藏导航栏下的黑线，写了很多代码

后来在iOS10上不好使了

1、之前用的这个方法：

- (void)viewWillAppear:(BOOL)animated{
    [super viewWillAppear:animated];

    [self.navigationController.navigationBar.subviews enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
        if ([obj isKindOfClass:NSClassFromString(@"_UINavigationBarBackground")]){
            UIView * v = obj;
            if (v.subviews.count)
            {
                navBottomLine = [v.subviews firstObject];
            }
            * stop=YES;
        }
    }];
    navBottomLine.hidden = YES;
}

2、iOS10出来之后，@"_UINavigationBarBackground" 变成了@"_UIBarBackground"，代码改成这样：

#define iOS10 ([[UIDevice currentDevice].systemVersion intValue]>=10?YES:NO)
- (void)viewWillAppear:(BOOL)animated{
    [super viewWillAppear:animated];
    
    [self.navigationController.navigationBar.subviews enumerateObjectsUsingBlock:^(UIView *view, NSUInteger idx, BOOL *stop) {
        if (iOS10) {
            //iOS10,改变了导航栏的私有接口为_UIBarBackground
            if ([view isKindOfClass:NSClassFromString(@"_UIBarBackground")]) {
                
                [view.subviews firstObject].hidden = YES;
            }
        }else{
            //iOS10之前使用的是_UINavigationBarBackground
            if ([view isKindOfClass:NSClassFromString(@"_UINavigationBarBackground")]) {
                
                [view.subviews firstObject].hidden = YES;
            }
        }
    }];
}

3、可不可以精简一下呢：

**如果设置了
[UINavigationBar appearance].translucent = NO;
**

- (void)viewWillAppear:(BOOL)animated{
    [super viewWillAppear:animated];
    
    self.navigationController.navigationBar.subviews[0].subviews[0].hidden = YES;
}

否则

- (void)viewWillAppear:(BOOL)animated{
    [super viewWillAppear:animated];
    
    self.navigationController.navigationBar.subviews[0].subviews[1].hidden = YES;
}

隐藏黑线之前和之后对比图

对比图

共

同

进

步

给个喜欢喔O(∩_∩)O