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Access Container View Controller from Parent iOS

in iOS6 I noticed the new Container View but am not quite sure how to access it's controller from the containing view.

Scenario:

I want to access the labels in Alert view controller from the view controller that houses the container view.

There's a segue between them, can I use that?

Prevent segue in prepareForSegue method?

Is it possible to cancel a segue in the prepareForSegue: method?

I want to perform some check before the segue, and if the condition is not true (in this case, if some UITextField is empty), display an error message instead of performing the segue.

Container View Controller Examples [closed]

Can anyone point me to any good examples of creating a Custom View Controller as a Container View Controller? The only documentation I can find is a couple of paragraphs in the UIViewController Class Reference. I feel I need a little more information than that and an example implementation would be nice. Google has turned up nothing at all.

I am specifically interested in the method:

transitionFromViewController:toViewController:duration:options:animations:completion:

iOS5 Storyboard UIViewController which init method is called by the storyboard?

Which init method is called by the storyboard for UIViewControllers added to the storyboard?

What does addChildViewController actually do?

I'm just dipping my feet for the first time into iOS development, and one of the first things I've had to do is implement a custom container view controller - lets call it SideBarViewController - that swaps out which of several possible child view controllers it shows, almost exactly like a standard Tab Bar Controller. (It's pretty much a Tab Bar Controller but with a hideable side menu instead of a tab bar.

As per the instructions in the Apple documentation, I call addChildViewController whenever I add a child ViewController to my container. My code for swapping out the current child view controller being shown by the SideBarViewController looks like this:

- (void)showViewController:(UIViewController *)newViewController {
    UIViewController* oldViewController = [self.childViewControllers 
                                           objectAtIndex:0];

    [oldViewController removeFromParentViewController];
    [oldViewController.view removeFromSuperview];

    newViewController.view.frame = CGRectMake(
        0, 0, self.view.frame.size.width, self.view.frame.size.height
    );
    [self addChildViewController: newViewController];
    [self.view addSubview: newViewController.view];
}

Then I started trying to figure out just what addChildViewController does here, and I realised that I have no idea. Besides sticking the new ViewController in the .childViewControllers array, it seems to have no effect on anything. Actions and outlets from the child controller's view to the child controller that I've set on the storyboard still work just fine even if I never call addChildViewController, and I can't imagine what else it could affect.

Indeed, if I rewrite my code to not call addChildViewController, and instead look like this...

- (void)showViewController:(UIViewController *)newViewController {

    // Get the current child from a member variable of `SideBarViewController`
    UIViewController* oldViewController = currentChildViewController;

    [oldViewController.view removeFromSuperview];

    newViewController.view.frame = CGRectMake(
        0, 0, self.view.frame.size.width, self.view.frame.size.height
    );
    [self.view addSubview: newViewController.view];

    currentChildViewController = newViewController;
}

... then my app still works perfectly, so far as I can tell!

The Apple documentation doesn't shed much light on what addChildViewController does, or why we're supposed to call it. The entire extent of the relevant description of what the method does or why it should be used in its section in the UIViewController Class Reference is, at present:

Adds the given view controller as a child. ... This method is only intended to be called by an implementation of a custom container view controller. If you override this method, you must call super in your implementation.

There's also this paragraph earlier on the same page:

Your container view controller must associate a child view controller with itself before adding the child’s root view to the view hierarchy. This allows iOS to properly route events to child view controllers and the views those controllers manage. Likewise, after it removes a child’s root view from its view hierarchy, it should disconnect that child view controller from itself. To make or break these associations, your container calls specific methods defined by the base class. These methods are not intended to be called by clients of your container class; they are to be used only by your container’s implementation to provide the expected containment behavior.

Here are the essential methods you might need to call:

addChildViewController:
removeFromParentViewController
willMoveToParentViewController:
didMoveToParentViewController:

but it doesn't offer any clue as to what the 'events' or 'expected containment behavior' that it's talking about are, or why (or even when) calling these methods is 'essential'.

The examples of custom container view controllers in the "Custom Container View Controllers" section of the Apple documentation all call this method, so I assume that it serves some important purpose beyond just popping the child ViewController onto an array, but I can't figure out what that purpose is. What does this method do, and why should I call it?

topLayoutGuide in child view controller

I have a UIPageViewController with translucent status bar and navigation bar. Its topLayoutGuide is 64 pixels, as expected.

However, the child view controllers of the UIPageViewController report a topLayoutGuide of 0 pixels, even if they're shown under the status bar and navigation bar.

Is this the expected behavior? If so, what's the best way to position a view of a child view controller under the real topLayoutGuide?

(short of using parentViewController.topLayoutGuide, which I'd consider a hack)

How to tell if UIViewController's view is visible

I have a tabbar application, with many views. Is there a way to know if a particular UIViewController is currently visible from within the UIViewController? (looking for a property)

iOS - Calling App Delegate method from ViewController

What I am trying to do is click a button (that was created in code) and have it call up a different view controller then have it run a function in the new view controller.

I know it could be done relatively easily in IB but that isn't an option.

An example of what I want to do would be if you had two view controllers one with a splash screen of house. The other view controller had a walk through of the house on it that you could go through all the rooms in a set order. The splash screen would have buttons for each room that would allow you to jump to any point on the walk through.

How do I create a custom iOS view class and instantiate multiple copies of it (in IB)?

I am currently making an app that will have multiple timers, which are basically all the same.

I want to create a custom class that uses all of the code for the timers as well as the layout/animations, so I can have 5 identical timers that operate independently of each other.

I created the layout using IB (xcode 4.2) and all the code for the timers is currently just in the viewcontroller class.

I am having difficulty wrapping my brain around how to encapsulate everything into a custom class and then add it to the viewcontroller, any help would be much appreciated.

Explaining difference between automaticallyAdjustsScrollViewInsets, extendedLayoutIncludesOpaqueBars, edgesForExtendedLayout in iOS7

I have been reading a lot about iOS7 UI transition.

I am not able to get what these three properties automaticallyAdjustsScrollViewInsets, extendedLayoutIncludesOpaqueBars, edgesForExtendedLayout??

For example I am trying to make my view controllers start below the status bar but I am not able to achieve it.

UIViewController. viewDidLoad vs. viewWillAppear: What is the proper division of labor?

I have always been a bit unclear on the type of tasks that should be assigned to viewDidLoad vs. viewWillAppear: in a UIViewController subclass. For example, I am doing an app where I have a UIViewController subclass hitting a server, getting data, feeding it to a view and then displaying that view. What are the pros and cons of doing this in viewDidLoad vs. viewWillAppear?

Thanks in advance.

Cheers, Doug

Looking to understand the iOS UIViewController lifecycle

Could you explain me the correct manner to manage the UIViewController lifecycle?

In particular, I would like to know how to use Initialize, ViewDidLoad, ViewWillAppear, ViewDidAppear, ViewWillDisappear, ViewDidDisappear, ViewDidUnload and Dispose methods in Monotouch for a UIViewController class.

Thank you in advance.

Get to UIViewController from UIView?

Is there a built-in way to get from a UIView to its UIViewController? I know you can get from UIViewController to its UIView via [self view] but I was wondering if there is a reverse reference?

iPhone how to check the type of an Object?

I want to check the type of an Object. How can I do that?

The scenario is I'm getting an object. If that object is of type A then do some operations. If it is of type B then do some operations. Currently the type of the object is C that is parent of A and B.

I have two classes AViewController andBViewController. The object I'm getting in UIViewController. Now how to check whether the object is AViewController or BViewController?

How to identify previous view controller in navigation stack

I have 2 seperate navigationcontrollers, one with RootViewController A and the other with RootViewController B.

I am able to push ViewController C onto either A or B's navigation stack.

Question: When I am in ViewController C, how can I find out if I am in the stack belonging to A or B?