Question

I have the following view controller structure in my app:

A container view controller with a UIToolBar (which is not a navigation bar) has a UIPageViewController embedded and this UIPageViewController presents additional child view controllers:

container view controller (toolBar) -> PageViewController -> ViewController 1,
                                                             ViewController 2

I would like to add and remove buttons (BarButtonItems) to and from the toolbar on the container view controller depending on the child view controllers 1 and 2 presented.

1. How would you recommend that the child view controllers 1 and 2
   access the toolbar in the container view controller to add and
   remove buttons?

2. It seems that the toolbarItems property in the container view
   controller is always 0 even though there are buttons in it. Any
   ideas on why this could be? Is the toolbarItems property <> 0
   only for navigation bars?

Edit

Based on the suggestion from user DBD I have added the following methods to the view controller CompanyViewController which has the toolbar and is the base class for my view controllers in a split views detail window (all my detail view controller inherit from CompanyViewController). One of these detail view controllers is used as a content view controller with a page view controller and the child view controllers described above.

CompanyViewController:

- (void)addToolBarItems:(NSArray *)buttonArray
{
    NSMutableArray *items = [[self.toolbar items] mutableCopy];
    
    [buttonArray enumerateObjectsUsingBlock:^(UIBarButtonItem *barButtonItem, NSUInteger idx, BOOL *stop) {
        if (! [items containsObject:barButtonItem] ) [items insertObject:barButtonItem atIndex:0];
    }];
    [self.toolbar setItems:items animated:NO];
}

- (void)removeToolBarItems:(NSArray *)buttonArray;
{
    NSMutableArray *items = [[self.toolbar items] mutableCopy];
    
    [buttonArray enumerateObjectsUsingBlock:^(UIBarButtonItem *barButtonItem, NSUInteger idx, BOOL *stop) {
        if ( [items containsObject:barButtonItem] ) [items removeObjectAtIndex:idx];
    }];
    [self.toolbar setItems:items animated:NO];
}

This is how I try to access the CompanyViewController from my child controllers:

- (CompanyViewController*)parentViewControllerWithToolbar
{
    UIViewController *parentPageViewController = self.parentViewController;
    CompanyViewController *parentContentViewController = (CompanyViewController*)parentPageViewController.parentViewController;
    return (CompanyViewController*)parentContentViewController;
}

However, when trying to call the addToolBarItems method from the child view controller I can’t get the method in Xcodes’s autocomplete: It seems that I have no access to this method even though I imported #import "CompanyViewController.h".

Any suggestions on what I might be missing here?

Answer 1

I would suggest not accessing the toolbar directly. Instead, I’d suggest the container class having public methods like

- (void)addToolBarItem:(UIBarButtonItem *)button atIndex:(int)index;
- (void)removeToolBarItemAtIndex:(int)index;

Then all your child has to do is get the parent, possibly do a type cast and call the method.

Encapsulating your UI changes like this remove the need for potentially duplicate code in your child classes to modify the toolbar, protect much of your code from possible API changes by Apple and allow you to easily decide to swap out the tool bar to something like a custom control in the future without causing ripple code change effects.

EDIT:

I thought you were using a container view controller, not a UISplitViewController. I’m going to re-state my understanding so you can tell me if I got it wrong.

You have a UISplitViewController displaying a “master” and “detail” views. You want the detail view to call back to the master and request a toolbar change.

In detail view controller, you want the master, but calling “parent” just gives you the UISplitViewController. So you have to access the split view controller and get the master view controller from there.

MasterViewController *foo = [self.splitViewController.viewControllers objectAtIndex:0];
[foo removeToolBarItems:bar];

Which says, go get the UISplitViewController which I belong to (same as calling parent), then access the array of view controllers it holds. Take the first item in the array and assign as your master view controller. From the docs on the UISplitViewController

viewControllers
The array of view controllers managed by the receiver.

@property(nonatomic, copy) NSArray *viewControllers

Discussion
The
array in this property must contain exactly two view controllers. The
view controllers are presented left-to-right in the split view
interface when it is in a landscape orientation. Thus, the view
controller at index 0 is displayed on the left side and the view
controller at index 1 is displayed on the right side of the interface