IOS prepareForSegue pass a data successfully but viewdidload clear it? - ios

Question

In UIViewController A I performSegue to UIViewControllerB.And in the prepaerForSegue function of A, I use set function set a strong variable 's value of B. However, when the B's viewDidLoad() called, the value is nil.
Anybody help me and tell me why?
my code is:
UIViewController A:
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
CXPWDViewController *cxpwdViewController=[[CXPWDViewController alloc] init];
//I can't use the segue.desinationViewController, cause it is a present modally , the desinationViewController is navigationViewController.
[cxpwdViewController setAction:#"EnterPasscode"];//here the cxpwdViewController .action is #"EnterPasscode"
}
UIViewController B:
-(void) viewDidLoad()
{
[super viewDidLoad];// here the cxpwdViewController .action is nil; Why?
}

Answer 1

If you are presenting an UINavigationViewController, then the rootViewController controller should be your CXPWDViewController. So that you can typeacast the same. Since you are creating an anaother viewcontroller instance you are not getting the value.Try this code.
UIViewController A:
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
if([[segue destinationViewController] isKindOfClass:[UINavigationViewController class]])
{
UINavigationViewController* destinationNavController =(NavigationViewController*)[segue destinationViewController];
CXPWDViewController *cxpwdViewController=(CXPWDViewController*)[destinationNavController.viewControllers firstObject];
if([cxpwdViewController isKindOfClass:[CXPWDViewController class]])
{
[cxpwdViewController setAction:#"EnterPasscode"];
}
}
}

Answer 2

CXPWDViewController *cxpwdViewController=[[CXPWDViewController alloc] init];
//I can't use the segue.desinationViewController
I don't know why you think you can't use the segue destination view controller. But in any case you certainly can't do what you want to do this way. You are creating a completely different CXPWDViewController - and then destroying it an instant later. You won't get far that way!