Navigate to RootViewController from ModalViewController - ios

Question

I have an app with 3 view controllers. A is the root, B is next and C is a modal view that appears / transitions when a button on B is clicked. What I want to do is sometimes move from C to A directly when a button on C is clicked (other times, the C->B transition should happen, which is ok). I've tried various options and incorporated info from different SO posts but in the end, stuck at the scenario where the direct transition from C to A happens but does show B momentarily.
Is there a way I can remove this momentary B appearance altogether. Also, I do need to have animations when the user goes from B to C or from C to B. It is the C to A transition that need not have an animation if there is a limitation there.
Hopefully you can chip in... have copied relevant code and further details below.
ViewControllerC.h:
#protocol ViewControllerCDelegate <NSObject>
- (void)didNavigateBackFromViewC:(ViewControllerC *)viewControllerC;
#end
#interface ViewControllerC : UIViewController
#property (nonatomic, weak) id < ViewControllerCDelegate > viewCDelegate;
#end
ViewControllerC.m:
- (IBAction)navigateToViewA:(id)sender
{
[self.viewCDelegate didNavigateBackFromViewC:self];
}
For the B->C and C->B transitions, I've used a separate transitioning controller that is a delegate of ViewControllerB. Also, ViewControllerB is a delegate of UIViewControllerTransitioningDelegate... I've not included those details for the sake of simplicity here but hopefully am able to convey the problem here about the C->A transition.
ViewControllerB.h:
#interface ViewControllerB () <ViewControllerCDelegate>
#end
ViewControllerB.m:
- (void)didNavigateBackFromViewC:(ViewControllerC *)viewControllerC
{
__block ViewControllerB *me = self;
[viewControllerC dismissViewControllerAnimated:YES completion:^{
[me.navigationController popToRootViewControllerAnimated:YES];
}];
}

Answer 1

really interesting question #vikram17000. First of all, you might want to try unwind segues, it seems that they can do what you want but I haven't tested that. It appered you were going the programmatic route, and here's what i found. I split (what I called) the 'back' and 'home' actions into two separate actions. Here's my ViewControllerC code:
-(IBAction)goBack:(id)sender
{
[self dismissViewControllerAnimated:YES completion:nil];
}
-(IBAction)goHome:(id)sender
{
[self.delegate ViewControllerCWillGoHome:self];
[self dismissViewControllerAnimated:YES completion:nil];
}
ViewControllerB is the delegate that gets the -...WillGoHome, and it popsToRootVC before VC C dismisses. This gets the behavior we want, C animates out and A is left - yay! Unfortunately there's a catch -
Unbalanced calls to begin/end appearance transitions for ViewControllerB: 0x7fc3c857ca80.
So is it possible? Yes. Does the os like it? No it does not. Hopefully this helps you get going though.

Answer 2

I've created sample project for your question.
There is protocol GoBackProtocol which contains method
-(void)controller:(UIViewController *)controller didPressBackButton:(UIButton *)button;
A and B controllers adopt GoBackProtocol. B controller implements -controller:didPressBackButton: method and decides based on button parameter what to do: hide presented controller with animation or hide it without animation and forward call to his delegate, which is controller A.
- (void)controller:(UIViewController *)controller didPressBackButton:(UIButton *)button
{
ViewControllerC *modalController = (ViewControllerC *)controller;
if (button == modalController.buttonB)
{
[controller.presentingViewController dismissViewControllerAnimated:YES completion:nil];
}
else if (button == modalController.buttonA)
{
[controller.presentingViewController dismissViewControllerAnimated:NO completion:nil];
[self.delegate controller:self didPressBackButton:nil];
}
}
Controller A implements -controller:didPressBackButton: as well and pops viewController B.
- (void)controller:(UIViewController *)controller didPressBackButton:(UIButton *)button
{
[self.navigationController popViewControllerAnimated:YES];
}
All Together it makes desired effect.

Answer 3

Please forget all custom protocol solutions here. Apple says:
The presenting view controller is responsible for dismissing the view controller it presented.
IMO you have at least two options here:
1) You could add the close button on C to public interface like
#property (nonatomic, strong, readonly) UIButton *closeButton;
Set the target differently and use a combination of dismissViewControllerAnimated:completion: and popToRootViewControllerAnimated: as in your method didNavigateBackFromViewC
2) You could use self.navigationController.presentingViewController in C to get access to the non-modal viewcontrollers.
As non-official option you could set the viewcontrollers array on a UINavigationController instance directly. Then you will get a Push Animation from C to A.

Answer 4

I haven't fully testing this out yet but results so far seem encouraging. Given that I wanted to be able to transition to B or C from A, and that B and C could navigate between each other, I've started playing around with making ViewControllerA as the container view controller for ViewControllerB and ViewControllerC. That allows me easy access to B / C from A, as well as the ability to transition between B and C seamlessly using custom transitions.