MyViewController.xib has File's Owner class set to MyViewController (a subclass of UIViewController) and File's Owner view connected to a UIView containing some subviews.
OtherViewController.xib has File's Owner class set to UIViewController and File's Owner view connected to an empty UIView.
Is it possible in Interface Builder to embed MyViewController's view inside the view in OtherViewController.xib?
I tried adding an instance of MyViewController into OtherViewController.xib, but I can't drop it inside the view (because it's not a UIView) and I can't get to the view that was associated with MyViewController in MyViewController.xib (only the view controller itself, and nothing it's connected to, makes it over to OtherViewController.xib).
You probably do not want to do this. Follow the warning in the View Controller Programming Guide:
Note: If you want to divide a view hierarchy into multiple subareas and manage each one separately, use generic controller objects (custom objects descending from NSObject) instead of view controller objects to manage each subarea. Then use a single view controller object to manage the generic controller objects.
A UIViewController subclass whose view does not fill the window will not behave as you might expect. It will not receive view controller lifecycle messages, rotation messages, or have its parentView/navigation/tabBarController properties set correctly.
A UITableViewCell should not be the view for a UIViewController. It might have some controller object responsible for managing its behavior (though I suspect this behavior can probably all be contained within the cell view itself) but that controller should not inherit from UIViewController.
This has changed since some of the other answers were posted - you want to take a look at the latest documentation for UIViewController, particularly the guide section "Presenting View Controllers from Other View Controllers" and the class reference guide section "Implementing a Container View Controller". Also, there's a video from WWDC 2012 covering the topic on iTunes: Session 236 - The Evolution of View Controllers on iOS. (The video is very useful, it's not just a general overview.)
You can put it all in one xib. For example, just put it all in your MainWindow.xib.
This can be done programmaticly by adding a reference in OtherViewController to MyViewController. This is perhaps a bit messy and does in some way lead me to ask why you would want to do this but... I will trust that you know what you're doing.
Warning. Because 'Other' will contain a reference to 'My' you will want retain My inside Other. but Do not, I repeat do not retain 'Other' inside of 'My' this kind of cycle will lead to errors.
Good luck and don't forget to vote
ps if you have a little more detail I may be able to help you sort out a better design so that this sort of thing can be avoided :)
Related
I have an WizardSequenceViewController with an IBOutlet WizardView *_wizardView. In many WizardSequenceViewController.xib file I have the view outlet connected to the File's Owner - WizardSequenceViewController. I have a subview of that view defined with the class attribute set to WizardView. I have connected that WizardView to the outlet in the File's Owner. Finally, in my WizardView.xib I have a UILabel that I have placed in the file to test if the view is being rendered. When I select the WizardSequenceViewController from my tab bar, I see the superview view but not the subview _wizardView. When I set a breakpoint in my -(id)initWithCoder method in my WizardView.m file I see it stop there, so I know that it is calling that initializer (and thus it should be using the xib to load that file). I have tried many iterations and variations to get this thing to work but I can't and I am going crazy. Does anybody have any ideas?
From Apple doc "View Controller Basics, About Custom View Controllers":
The one-to-one correspondence between a view controller and the views in its view hierarchy is the key design consideration. You should not use multiple custom view controllers to manage different portions of the same view hierarchy. Similarly, you should not use a single custom view controller object to manage multiple screens worth of content.
Note: If you want to divide a view hierarchy into multiple subareas and manage each one separately, use generic controller objects (custom objects descending from NSObject) instead of view controller objects to manage each subarea. Then use a single view controller object to manage the generic controller objects.
Maybe you can't do a view-and-subview outlet setup in a view controller. And I'm not sure assigning the subview outlet to a separate NSObject subclass would work either, because how would you present it? Could you write your subview programmatically, using initWithFrame and addSubview, instead of making it an outlet? Or, if you really want to set it up graphically, could you assign it to a separate view controller as owner? Then the top view controller will call presentModal on the sub view controller. Or, if all you need is a UILabel as a subview, just add the label to the main view?
Even I faced a similar issue. But got it resolved by following steps given in the following link. Hope it helps.
http://blog.yangmeyer.de/blog/2012/07/09/an-update-on-nested-nib-loading
I have created Storyboard with several views calling each other, now I need to create the code
I notice that XCode didn't created .h and .m controller files for each View from storyboard.
Should I create them manually?
Should I keep only one controller? (or few depending of separation of concerns on MVC)
Is there a pattern for developing this?
thanks
The usual approach is one view controller pr. screen full of content. You can imagine having one view controller for a tableview, with any sort of content, and then another view controller that presents that content in a new screen full of content if a row is pressed.
Normally when you have subviews inside of your view controllers, you wire them up in interfacebuilder. Then for instance if you want to populate a view that has a uiimageview and a uiactivityindicatorview inside it, you can control their behavior and how their populated from the view controllers code. You could also if you want something very generic and you feel that one view will probably take up a lot of code in your view controller, create a uiview subclass for it, and then set the class in interface builder.
Did this help? Please let me know if you need more clarification.
It's entirely up to you whether you have a ViewController for each view. If you have many views I would recommend it. Even if you have 2 or 3 views you probably still should. Things can get really confusing when each view has a different task but all have similar IBOutlets.
TLDR; Personally, I would say it was good practice to have a ViewController for each view if each view has a separate task.
In the app represented by the image below, I'm currently using three UIViewControllers: One master view controller, one for the main menu, and one for a settings screen which is launched by the main menu. As I'm learning more about how UIViewController works and what it's designed for, I'm questioning the wisdom of my architecture.
It seems to me that the main point of subclassing is to be able to override the methods which get called automatically during the life cycle of the controller: viewDidAppear, viewWillAppear, willRotateToInterfaceOrientation, etc. It appears that these methods are only called if the UIViewController (or subclass) is part of the UIViewController hierarchy. Therefore, there's no point in subclassing UIViewController unless I'm going to use one of the standard means of creating a viewcontroller hierarchy i.e. UINavigationController, [UIViewController presentModalViewController] etc.
I'm wary of using the Cocoa-style means of adding view controllers to the hierarchy because they all seem to be very restrictive. For example, I could display my settings screen using [UIViewController presentModalViewController], but but I don't want it to obscure the entire screen. There's background animation which I want the user to be able to interact with even while the settings screen is visible.
Here are my questions:
1) Is it silly to subclass UIViewController unless I'm going to be adding it to the viewController hierarchy via one of Apple's techniques?
2) Am I correct in my assumption that the built-in means of displaying new views are too restrictive for me, and in order to have the flexibility I want, I'm going to need to just load views via [view addSubview]
3) If it's true that subclassing UIViewController makes no sense for my menu and settings views, how should I avoid having all of my code in one monster UIViewController subclass. Should I just subclass NSObject, add the appropriate IBOutlets and IBActions and pass that in as the File's Owner when I load the nib using [NSBundle loadNibNamed]?
Good question. First, a point of clarity: What you refer to as "one of Apple's techniques" is referred to in the UIViewController Programming Guide as "indirect presentation", and includes things like modal presentation, being pushed on a navigation stack, presenting a popover controller, etc. Basically all of these view controller methods are considered "indirect" presentation methods, while the use of -addSubview: (something like [someView addSubview:myViewController.view]) is considered "direct" presentation.
From said programming guide: (Giant Block Quote...)
It is recommended that you use only
the suggested techniques for
displaying the views of your view
controllers. In order to present and
manage views properly, the system
makes a note of each view (and its
associated view controller) that you
display directly or indirectly. It
uses this information later to report
view controller-related events to your
application. For example, when the
device orientation changes, a window
uses this information to identify the
frontmost view controller and notify
it of the change. If you incorporate a
view controller’s view into your
hierarchy by other means (by adding it
as a subview to some other view
perhaps), the system assumes you want
to manage the view yourself and does
not send messages to the associated
view controller object. (emphasis mine)
Apart from your setting up your
application’s initial interface, most
other views are presented indirectly
through their view controller objects.
All that is to say that you are correct in thinking that all of those UIViewController messages will be wasted if you if simply add the view to a view hierarchy directly, and take no other further action (key window being the exception). That quote also mentions that it is most common to use indirect presentation.
1) I hesitate to make a blanket statement and say "Yes, in all cases, it is silly to subclass UIViewController unless you're presenting it indirectly." I'm sure there is some good use for it somewhere. I'll settle for saying that I have personally never done so.
2) Absolutely, I would not use a UIViewController subclass here.
3) Allow me to direct your attention to another area of The Programming Guide:
In iPhone applications, the views in a
view hierarchy traditionally cover the
entire screen... If you want to divide
a view hierarchy into multiple
subareas and manage each one
separately, use generic controller
objects (custom objects descending
from NSObject) instead of view
controller objects to manage each
subarea. Then use a single view
controller object to manage the
generic controller objects.
That pretty clearly syncs up with what you're wanting to do here. You're dead on with your self suggested approach. That "Settings Screen launched by main menu" should be managed by a generic controller object descending from NSObject, which is in turn managed by your full-screen UIViewController subclass.
I've got a Table view and it's the child of the View ( see the IB hierarchy ) :
I want to start customizing the tableCells, so I assume I'll have to add a tableViewController . Where would I start in this instance ? the TableViewcontroller can't be a child of the MainViewController, can it ?
Cheers,
You would need to add a table view controller at the top level.
Then drag connections from the table to the controller of datasource and delegate
Then drag connections from the controller to the view for "view"
Then change the class of the controller you added (it's the last tab in the inspector) to your custom UITableViewController class (if you don't subclass it it does nothing)
Then make sure that you somehow retain the controller when the nib is loaded. Easiest way is with an IBOutlet in the file's owner.
Sorry if this is a bit general, but the specifics would consume pages. I don't recommend this approach unless you have some experience with this and know what most of the above means, in which case it's possible and sometimes desirable to do this, and good job if you do.
The easiest method, if you just want a simple table view, no special circumstances, is to use the File>New File>UITableViewController with xib for user interface, then go from there with the file it makes, but that isn't your question, so I have answered as best I can.
It would be easier to build a tableViewController class with a table inside that and add the tableViewController to the view instead of reverse-engineering it. The tableViewController will have all your delegate and datasource functions for your table fairly mapped out so you can move whatever you already have into those functions.
As for custom tableViewCells, here's a great tutorial from pragmaticstudio.com on how to do so. He walks you through all the aspects of building a tableViewController and also how to customize your cells in IB.
I have a view which I built in Interface builder with a tableview and associated outlets etc, to display a list of items. Clicking on an item brings up the detail of that item.
I now want to build a very similar view with a list of the same kinds of items and some additional controls and different behavior on cell selection. In this case, if the user clicks on the item, they will effectively be using that item as a template to create a new item. Or, they can click on a button to create a new item. Aside from this, there is a lot of logic I want to reuse from the original view - for example the items are location dependent, and there is a background thread that updates the location information.
It seems like the natural thing to do would be to subclass the original viewcontroller, and build a second view layout using IB. However, before I embark on this I'm wondering if this is possible/recommended practice? Will IB recognise the IBOutlets in the superclass and let me wire them up?
IB will recognise the IBOutlets defined in the superclass.
You do it all the time: The outlet for the view in UIViewController is defined in a superclass you subclass for each of your View Controllers.
pgb is correct. IB will recognise outlets in the superclass
As for whether subclassing the controller is a good or bad idea, I'm not sure. Apple suggests subclassing NSArrayController in order to change sorting/filtering behaviour. A view controller is different to an array controller, but I dare say that subclassing the view controller is probably the correct thing to do.