当我们从nsobject类获得响应时，如何从nsobject类导航回viewcontroller

Question

我想从nsobject类回到我的viewcontroller。我该如何导航。现在正在尝试

UIWindow *window = [UIApplication sharedApplication].keyWindow;   
UIViewController *rootVC = [window rootViewController];         
UIStoryboard *stroyBoard = rootVC.storyboard;         
MyVC *myVC = [stroyBoard instantiateViewControllerWithIdentifier:@"MyVC"];         
[myVC transactionStatus:YES receipeNo:recNum];         
[rootVC presentViewController:myVC animated:YES completion:nil];

但是它杀死了我以前的Navigationcontroller流。请帮帮我