xcode storyboard Container View - How do I access the viewcontroller

Question

I'm trying to use storyboard and get things working properly. I've added a a Container View to one of my existing views. When I try to add a reference to this in my view controller .h file (ctrl-drag), I get a IBOutlet UIView *containerView. How do I get a reference to the container view's view controller instead? I need the container view controller so I can set it's delegate to my view's controller so they can "talk" to each other.

I have my story board setup as:

And its referenced in my .h file as:

Notice in the .h that is is a UIView, not my InstallViewController for the view. How do I add a reference to the view controller? I need to be able to set its delegate.

Randyranee

Here's the final, ultimate, last-word, maintained, tutorial on that! https://mcmap.net/q/17273/-how-to-add-a-subview-that-has-its-own-uiviewcontroller-in-objective-c There are some subtleties you need to know about, they are all explained there in detail and clearly. – Meat

Answer 1

There is another solution by specifying an identifier for the embed segue(s) and retrieve the corresponding view controllers in method prepareForSegue:

The advantage of this way is that you needn't rely on a specific order in which your child view controllers are added due to the fact that each child view controller is embedded via an unique segue identifier.

Update 2013-01-17 - Example

- (void) prepareForSegue:(UIStoryboardSegue*)segue sender:(id)sender
{
    // -- Master View Controller
    if ([segue.identifier isEqualToString:c_SegueIdEmbedMasterVC])
    {
        self.masterViewController = segue.destinationViewController;
        // ...
    }
    // -- Detail View Controller
    else if ([segue.identifier isEqualToString:c_SegueIdEmbedDetailVC])
    {
        self.detailViewController = segue.destinationViewController;
        // ...
    }
}

c_SegueIdEmbedMasterVC & c_SegueIdEmbedDetailVC are constants with the corresponding ID of the segue IDs defined in the storyboard.

Worldwide

Sorry for the late update. I'm sure you managed the problem by yourself in the meantime but eventually the example code helps other ones in the future. – Worldwide

God answer. I Tried that trick before, and only after reading this answer I realized that it only works if you setup Segue Identifiers. However I would use isKindOfClass: instead. – Songwriter

Why are there two view controllers (detail and master)? Isn't it just the one view controller in the container? What other segue are you referring to? – Schnorrer

@shim: In my example project I had a kind of split view with a master and a detail view controller hosted in 2 separate container views - therefore the two view controllers. – Worldwide

Its a shame that this is the best way of getting a reference to the child view controller. The whole point of the storyboards is to reduce boilerplate code like this. I could add the child view controller in viewDidLoad in fewer lines of code and it would be more maintainable than this. Anyone know if this fixed in XCode 6? – Alexandra

Answer 2

When you add a container view the xcode calls the UIViewController method addChildViewController:

In your case, you can get the container ViewController looking for it on the SplashViewController's list of childViewControllers, something like this:

for (UIViewController *childViewController in [self childViewControllers])
{
    if ([childViewController isKindOfClass:[InstallViewController class]])
    {
        //found container view controller
        InstallViewController *installViewController = (InstallViewController *)childViewController;

        //do something with your container view viewcontroller

        break;
    }
}

I had the same doubt yesterday :)

Nynorsk

I am trying to do something similar and what i don't get is the "vc" in InstallViewController *installViewController = (InstallViewController *)vc; – Ambrogio

You are right, it should've been "childViewController". I've just fixed in the post. Sorry for taking that much to reply. – Nynorsk

This approach feels a bit like a "workaround" to me. Doesn't it? – Flex

Well, it did the trick :) Does the prepareForSegue method is called when a Container View is added to another view? – Nynorsk

Answer 3

The answer of Vitor Franchi is correct but could be more performant and convenient. Especially when accessing the child view controller several times.

Create a readonly property

@interface MyViewController ()
@property (nonatomic, weak, readonly) InstallViewController *cachedInstallViewController;
@end

Then create a convenient getter method

- (InstallViewController *)installViewController
{
    if (_cachedInstallViewController) return _cachedInstallViewController;

    __block InstallViewController *blockInstallViewController = nil;
    NSArray *childViewControllers = self.childViewControllers;
    [childViewControllers enumerateObjectsUsingBlock:^(id childViewController, NSUInteger idx, BOOL *stop) {

        if ([childViewController isMemberOfClass:InstallViewController.class])
        {
            blockInstallViewController = childViewController;
            *stop = YES;
        }
    }];

    _cachedInstallViewController = blockInstallViewController;

    return _cachedInstallViewController;
}

From now on access the child view controller that way

[self.installViewController doSomething];

Zed

Answer 4

UIView* viewInsideOfContainer = installerView.subviews[0];

Will give you the UIView inside of the UIViewController that your controller UIView references. You can cast the subview to any type that inherits from UIView.

Ailbert

I'm not sure I like making that assumption, but it's useful to know. – Cryptoanalysis

That's not the universal way: view hierarchy can change and this method won't work. – Theatre

Answer 5

If the nib is loaded it will call addChildViewController as part of the initialisation process

so a performant solution could be also to overwrite

- (void)addChildViewController:(UIViewController *)childController

there you can catch your childController e.g. by comparing its Class and assign it to a property / ivar

-(void)addChildViewController:(UIViewController *)childController
{
    [super addChildViewController:childController];

    if([childController isKindOfClass:[InstallViewController class]])
    {
        self.installViewController = (InstallViewController *)childController;
    }

}

This will save your from iterating trough the childViewControllers.

Callean