How to make a high level controller load a view controller

Question

I have a high level controller class that is in charge of managing several classes and driving a state machine.

Part of the state logic involves the temporary display of a couple of different screens, there is a dedicated view controller for each of these screens and the high level controller creates these other controller classes and presents them as modal view controllers as necessary.

However one of these view controllers is very simple, it has a button and some text which can change as the state progresses. The high level controller is the class that knows what text to display at what stage and also it needs to know when the button has been pressed.

Therefore the view controller would need to present an API which the high level controller can call to set the text, and also the high level controller would need to be a delegate of the view controller so it can be called back when the button is pressed. This seems unnecessary plumbing which I'd like to remove.

So I could move the outlets and actions in the view controller into the high level controller so this plumbing isn't needed. But then there's nothing left in the view controller (its being instantiated from a nib). So I'd like to get rid of it entirely.

Then once its gone I was planning on having this in the high level controller:

UIViewController *vc = [[UIViewController alloc] initWithNibName:@"TheNib" bundle:nil];

or should it be:
UIViewController *vc = [[UIViewController alloc] init];
[[NSBundle mainBundle] loadNibNamed:@"TheNib" owner:vc options:nil];

[[UIApplication sharedApplication].delegate.window.rootViewController presentViewController: self.vc animated: NO completion:nil];

However how should IB be set up in order to achieve this - specifically a) what should the File's Owner be set to? b) what can the view within the IB be set to?

Note that the high level controller is already inheriting from another class and thus I cannot derive it from UIViewController thus it does not have a view property to connect to the view in IB.

Is there a easy way of connecting the xib contents to the UIViewController that is created within the high level view controller?

score 1 · Answer 1 · edited May 23 '17 at 10:29

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You can try to change the file owner or add an class object to your NIB…

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Just drag "Object" to the objects list and set the right class. Then, you can use IBactions connected to this object.

Maybe this question I made (and answered) can help you: Coordinating Controller design pattern in Cocoa Touch

edited May 23 '17 at 10:29

Community

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answered Jun 08 '12 at 21:39

Eduardo Russo

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Hmmm I'm getting an exception when I click the button which is connected to an outlet in the high level controller, if I instead connect the button to an outlet in the view controller everything is ok, switch it back to an outlet in the high level view controller and the exception returns: -[TileLayer RegisterButtonPressed:]: unrecognized selector sent to instance 0x1ae080' – Gruntcakes Jun 08 '12 at 22:28
I was having the exact same problem… an exception without any kind of explanation… check the answer I gave on my own post([Coordinating Controller design pattern in Cocoa Touch](http://stackoverflow.com/questions/10834826/coordinating-controller-design-pattern-in-cocoa-touch/10931366#10931366)), that I show what I did to stop this bug. To be honest, I don't really know what was wrong, but I managed to fix it. – Eduardo Russo Jun 08 '12 at 22:30

score 1 · Accepted Answer · answered Jun 08 '12 at 21:39

A view and its controller is an 'element of modularity' Thus, if the view has a button then the view's controller, not the parent, should be the target of the button. The view's controller, figuring that parents/others will be interested in button events, should define a delegate interface or a notification interface that parents/others can participate in.

In your case by 'removing unnecessary plumbing' you are 1) moving away from the 'element of modularity' and 2) creating difficulties that lead you to ask a question about a problem related to removing plumbing.

It is best just to use the standard patterns.

score 0 · Answer 3 · answered Jun 08 '12 at 21:47

If all your view is doing is displaying some text and a button why not replace it with an UIAlertView? It's a simple control for displaying some text and a button, or two, with a well defined interface for getting which button was pressed back.

Ofcourse this might not fit with your design as UIAlertView can't really be customized unless you use a 3rd party replacement (i.e. http://cocoacontrols.com/platforms/ios/controls/tweetbot-like-uialertview-and-uiactionsheet-replacement).

How to make a high level controller load a view controller

3 Answers3