XCode iPhone: hiding UIToolbar in parent UIViewController from child UIScrollView

Question

I have a project similar to Apple's PageControl example. I have a UIViewController "PhotoViewController" which contains a UIScrollView and a UIToolbar. The UIScrollView loads another XIB and UIViewController "PhotoScrollViewController".

In PhotoScrollViewController, I have a UIButton which displays an image. I have an IBAction on this button, and I would like to click on it to show/hide the UIToolbar in PhotoViewController.

In PhotoViewController.h I have

@interface PhotoViewController : UIViewController <UIScrollViewDelegate> {
  IBOutlet UIToolbar *toolBar;
  ..
}

@property (nonatomic, retain) UIToolbar *toolBar;

I have tried a few things in PhotoScrollViewController, such as importing PhotoViewController.h in PhotoScrollViewController.h and adding it to the interface, then attempting to access it through my function like:

@implementation PhotoScrollViewController

- (IBAction)toggleMenu {
  photoViewController.toolBar.hidden = NO;
}

But this doesn't work. I've also tried removeFromSuperView, and self.parentViewController, and some other things. I am not sure how to make this toolbar hidden (I've tried alpha as well, I just can't access the toolbar at all).

I tried adding a function to PhotoViewController instead, using toolBar.hidden = YES. This works if I execute the function from PhotoViewController, but it doesn't work if I access it from PhotoScrollViewController (with PhotoViewController *photoViewController in .h):

@implementation PhotoScrollViewController

- (IBAction)toggleMenu {
  photoViewController.toolBar.hidden = NO;
  [photoViewController toggleTopMenu];
  [[PhotoViewController alloc] toggleTopMenu];
}

@implementation PhotoViewController

- (IBAction)toggleTopMenu {
  toolBar.hidden = NO;
}

I also tried adding the toolbar to PhotoScrollViewController instead, and I can toggle it, but I can't figure out how to tell the main UIViewController to dismiss PhotoViewController... so whichever way I attack this problem I don't know how to communicate properly between UIViewControllers.. and the documentation I read seems to follow what I've tried.

Answer 1

Basically, your problem seems to be you cannot reference one controller from another. This can be done in various ways.

1: Create your controllers in your application delegate when loading the application, and expose references to them e.g. as properties of the delegate.

2: Pass references to the PhotoViewController when creating or showing the PhotoScrollViewController. You say this doesn't work:

 @implementation PhotoScrollViewController

 - (IBAction)toggleMenu {
     photoViewController.toolBar.hidden = YES;
 }

The only way this may not work if if your photoViewController reference is nil. Where/how do you set it?