- (void)useMethodToFindBlackLineAndHindWithHidden:(BOOL)hidden{ UIImageView* blackLineImageView = [self findHairlineImageViewUnder:self.navigationController.navigationBar]; //隐藏黑线(在viewWillAppear时隐藏,在viewWillDisappear时显示) blackLineImageView.hidden = hidden; } - (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; } - (void)viewWillAppear:(BOOL)animated{ [super viewWillAppear:animated]; //隐藏黑线 [self useMethodToFindBlackLineAndHindWithHidden:YES]; } - (void)viewWillDisappear:(BOOL)animated { [super viewWillDisappear:animated]; ///显示黑线 [self useMethodToFindBlackLineAndHindWithHidden:YES]; }