- (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;
}
viewDid 方法中调用：_navBarHairlineImageView = [self findHairlineImageViewUnder:self.navigationController.navigationBar];
will方法中
_navBarHairlineImageView.hidden = YES;
viewDisapp方法中
_navBarHairlineImageView.hidden = No;