开发中解决viewWillAppear失效问题

图片发自App

今天写个小demo出现viewWillAppear失效问题，于是就就找度娘解决了这个问题，还是度娘好，这里先给度娘点赞一下，废话不多说了，问题具体原因:
UINavigationController. 将UINavigationController的view作为subview添加到了其他viewController的view中。或者把UINavigationController添加到UITabbarController中了;
此时，NavigationController的stack里面的viewController就收不到 -(void)viewWillAppear:(BOOL)animated等4个方法的调用
错误报告:
[Warning: If the view belonging to a view controller is added to a view hierarchy directly, the view controller will not receive this message. If you insert or add a view to the view hierarchy, and it has a view controller, you should send the associated view controller this message directly. Failing to send the view controller this message will prevent any associated animation from being displayed]
看着英文头都晕+_+, 也不翻译了,具体解决这个问题有两种方法:

第一种:在viewWillAppear与viewWillDisappear把你的subCntlr的里面这两方法在调用一次即可--

-(void)viewWillAppear:(BOOL)animated
{
 [super viewWillAppear:animated];
[subCntlr viewWillAppear:animated];

}

-(void)viewWillDisappear:(BOOL)animated
{
 [super viewWillDisappear:animated];
 [subCntlr viewWillDisappear:animated];
}

第二种:把导航控制器上层controller设为UINavigationController的delegate--

nav.delegate = self;
@interface 
RootViewController : UIViewController  {
    UINavigationController *navController;
}
 
- (void
)navigationController:(UINavigationController *)navigationController 
    willShowViewController:(UIViewController *)viewController animated:(BOOL
)animated 
{
    [viewController viewWillAppear:animated];
}

- (void
)navigationController:(UINavigationController *)navigationController 
    didShowViewController:(UIViewController *)viewController animated:(BOOL
)animated 
{
    [viewController viewDidAppear:animated];
}