Objective-C页面消失或出现时，判断是pop还是push

• (void)viewWillDisappear:(BOOL)animated {
  NSArray *viewControllers = self.navigationController.viewControllers;//获取当前的视图控制其
  if (viewControllers.count > 1 && [viewControllers objectAtIndex:viewControllers.count-2] == self) {
  //当前视图控制器在栈中，故为push操作
  NSLog(@"push");
  } else if ([viewControllers indexOfObject:self] == NSNotFound) {
  //当前视图控制器不在栈中，故为pop操作
  NSLog(@"pop");
  }
  }

[self.navigationController setNavigationBarHidden:YES animated:animated];
设置是否隐藏导航栏，隐藏view界面上移

[self.navigationController.navigationBar setBarTintColor:KMainColor];设置导航栏的颜色

[self.navigationController.navigationBar setBarStyle:UIBarStyleBlackTranslucent];
设置导航栏的风格
UIBarStyleDefault：文字颜色为黑色
UIBarStyleBlack = 1,
UIBarStyleBlackOpaque = 1,
UIBarStyleBlackTranslucent = 2
文字颜色为白色

self.navigationController.navigationBar.translucent = YES;表示view从0，0开始
self.navigationController.navigationBar.translucent = NO;表示view从navigationBar下方开始