iOS隱藏導航欄下面的橫線

方法一：

[self.navigationController.navigationBar setBackgroundImage:[[UIImage alloc]init]forBarPosition:UIBarPositionAny barMetrics:UIBarMetricsDefault];
    [self.navigationController.navigationBar setShadowImage:[UIImage new]];

方法二：

1 聲明UIImageView變量,存儲底部橫線
@implementation MyViewController 
{
    UIImageView *navBarHairlineImageView;
}

2 在viewDidLoad中加入：
navBarHairlineImageView = [self findHairlineImageViewUnder:navigationBar];

3 實現找出底部橫線的函數
- (UIImageView *)findHairlineImageViewUnder:(UIView *)view {
    if ([view isKindOfClass:UIImageView.class] && view.bounds.size.height <= 1.0) {
            return (UIImageView *)view;
    }
    for (UIView *subview in view.subviews) {
        UIImageView *imageView = [self findHairlineImageViewUnder:subview];
        if (imageView) {
            return imageView;
        }
    }
    return nil;


4 最後在viewWillAppear，viewWillDisappear中處理
- (void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];
    navBarHairlineImageView.hidden = YES;
}

- (void)viewWillDisappear:(BOOL)animated {
    [super viewWillDisappear:animated];
    navBarHairlineImageView.hidden = NO;
}