iOS隐藏导航条1px的底部横线

@implementation MyViewController {

UIImageView *navBarHairlineImageView;

navBarHairlineImageView = [self findHairlineImageViewUnder:navigationBar];

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