IOS 使用 presentModalViewController 显示一些 Controller

Question

我使用 presentModalViewController 来显示一些 Controller 。

A Controller ://它将显示B的 Controller 并接收消息，当它收到消息时，我想知道B是否显示？

-(void)viewDidLoad{

     [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(recvPushMessage:) name:RECV_PUSH_MESSAGE_NOTIFY object:nil];

}
-(void)buttonAction(id)sender{
     B* b = [B alloc] init];
     UINavigationController *navigationController = [[UINavigationController alloc] initWithRootViewController:(UIViewController*)b];
     [self presentModalViewController:navigationController animated:YES];
     //release 
}
-(void)recvPushMessage{
   //i want to kown B is it show or not
   if(b is showing){
      //do something
   }
   else{
      //do something for A
   }

}

B Controller ://当B显示时，我不想在A中调用recvPushMessage。

 -(void)viewDidLoad{

     [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(recvPushMessage:) name:RECV_PUSH_MESSAGE_NOTIFY object:nil];

}
-(void)recvPushMessage{

   //do something for B
}

Answer 1

检查这是否是您正在寻找的，

-(void)recvPushMessage{

   if (self.presentedViewController) { //check if you have this model view controller
      //do something
   }
   else{
      //do something for A
   }
}

对于版本 < iOS 5.0，您可以使用 self.modalViewController .

更新:
对于第二个问题，您可以获取 topViewController导航 Controller 并将其与 C 进行比较。您可以使用类似 [self.modalViewController topViewController]检查它是否是C，然后继续。

例如:-

if ([[(UINavigationController *)self.modalViewController topViewController] isKindOfClass:[C class]])