I'm trying to add multiple views inside a UITabBarController. Currently my object hierarchy looks like this: UITabBarController -> UIViewController* -> UIView*. As a more concrete example, the first view controller for my UITabBarController is a UIViewController, and that has three subviews, which are controlled by a UISegmentedControl. Depending on what segment is selected, I push the corresponding view to the front.
I understand that I can use a UINavigationController to manage my three views; however, the data I wish to present is not really hierarchical.
Are there examples of container controllers other than UITabBarController or UINavigationController that I can use for this case? Or is there another approach I should use (I'm currently managing views manually).
Thanks!
Custom view controllers are covered in the View Controller Programming Guide.
If you wanted to change your layout to use the UINavigationController you could remove the segmented control view and have the first view be a table view inside a nav controller. The table would have the three options the segmented control had and tapping on them would push the view associated with that option. This way you've created a hierarchical view layout rather than using the segmented control, which is typically used to toggle functionality rather than control views.
If you choose to do this, these two guide sections would be a good place to start.
There's not really any supporting framework for this - usually you have to manage switching out views in a switched container view yourself.
One approach I have taken in the past is to maintain an array of ViewControllers for each switching view, and take the viewController.view to add as a subview of your switched container view. Then I write code around the switching of the view controllers to call viewWillAppear and viewWillDisappear on the contained view controllers as they are swapped in and out, that makes things much simpler since you can treat them totally separately.
You can write that class kind of generically and then re-use it.
Related
I am new in developing iOS apps. I am trying to develop a multiple views app. My doubt is how to manage a multiple views app with View Controller, I mean, I do not want to use Navigation Controller nor Tab Controller.
My idea is to show a first View to choose the language, and after this, I want to show some different profiles in a table view. When you choose the profile, you get into a menu where you have some different functionalities (Once in this menu, I might use Navigation Controller).
My problem is that I don't know how to manage these two first views. I don't know if I have to declare them in the appDelegate, or if I can do it nesting one to other, I mean, I do the first view, and when I pressed the button, I declare the new view. Once in the new view, when I pressed a row in the table view, I make the another view.
I know it is a little bit confusing, so I hope you could understand it quite well.
EDIT:
I want to clarify that I am not using storyboards. My main doubt is what to do with all de view controllers, Do I have to declare all of them in the appDelegate? or Can I declare each view in every controller?
If you are using storyboards, you can use Segue's to navigate between the views, so you would show your first view, then you could tie a button to the next view (by control dragging in storyboard). If you want to transition programmatically you can use the performSegueWithIdentifier method. You could use the same approach to get from your tableViewController to your next viewController by using the performSegueWithIdentifier method from within the tableViewController's didSelectRowAtIndexPath delegate method (i.e. when a user taps a cell).
That should get you started. Good luck!
EDIT:
You really should be using storyboards. It's the way to do things these days. If you refuse, then the best approach is to create a container view controller that manages your "children" view controllers. You can find information on doing this, as well as the methods needed to present/remove child view controllers here:
Custom Container View Controllers
You can use navigation controller with "hidden" property.
self.navController.navigationBarHidden = YES;
If you want to have two different views and transition between them, you will want to use UIViewControllers presented modally. Here is Apple's Guide to this.
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.
The View controller programming guide states this regarding view controller's usage:
Each custom view controller object you
create is responsible for managing all
of the views in a single view
hierarchy. In iPhone applications, the
views in a view hierarchy
traditionally cover the entire screen,
but in iPad applications they may
cover only a portion of the screen.
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.
I understand that if we use multiple custom view controller's to control the parts of a view (i.e. a view controller to manage subViews of a main view which in turn is managed by a view controller) the default methods like:
didReceiveMemoryWarnings
viewWillAppear
viewWillDisappear
viewDidUnload
etc. etc. will not be called.
Apart from this, is there any other solid reason why we should not be using multiple view controllers to manage the respective subviews of a view?
The documentation also provide an alternative solution which reads as:
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.
But there is no mention as to why multiple view controllers should not be preferred. My question is:
Why should not we prefer it this way?
I am concerned because I prefer using UIViewController's subclass to manage my views since I load them from nib each time and I segregate nibs for each view controllers. It becomes easy to cater the changes in later stages of the project. Is this wrong? Should I necessarily change my programming style, or is it ok if I go ahead with this approach?
Thanks,
Raj
Well, I'd say "as long as it works", you can keep on doing like you do !
But to keep things "cleaner", I'd use my own objects.
Since ViewControllers are designed with other general features in mind (like working with navigation controllers and tab bar controllers), which makes it a bit "heavy" for a simple usage, like you do.
Plus, like you mentioned, some events are only called when the viewController's view is added to the main window.
Can't you use your own objects with Interface Builder ? If you create one (or several) UIView IBOutlet(s), it should work the same.
I have an app that does use two UIViewControllers on a single screen. The child is a UITableViewController. I don't rely on any of the UIViewController behavior of the child -- only the UITableViewController methods. This is convenient because there are other cases where the child UITableViewController does manage the whole screen. And in that case, it does use the UIViewController methods. Questionable design? Maybe. It has worked fine for two years now. But I'm not sure I would recommend the pattern.
I'm tinkering with an iPad app that (like many iPad apps) doesn't use the UINavigation root view control system, so I don't have natural ownership for each app "view". I essentially have two basic views: a document list view, and a document edit view.
I'm playing with UIView animation for getting from a selected document to the edit view.
I also have a toolbar on top that exists (with different buttons) in both "views".
Because I don't have UINavigation running the show for me, I have a tendency to just throw more and more stuff into one NIB and one view controller that owns the whole container. But now I'm trying to figure out how to segue from the document list view to the edit view if the edit view lives inside a different NIB, preserving the toolbar too.
Anyone have thoughts or experience on app structures like this? I find the docs lacking on best practices around code/UI structure for anything except trivial one-screen apps or full-on navigation apps.
You're not "supposed" to have parent/child view controllers owning subcomponents of the same "screen" according to the docs, but this implies one massive honking view controller that basically contains the whole app, and that can't be right.
Not sure if there's a "right answer" to this; I'm looking for some intelligent examples or suggestions. Nobody's touched this question in months, so I'm adding a bounty to generate good chatter. :)
Thanks!
UPDATE: I'm not talking about a split view, which is clearly well handled by a split view controller. Instead, take a look at Apple's iWork apps (e.g. Pages) which have a document list view and an independent edit view, but these are related by animation.
Maybe the real question here is: how would you (or could you even?) build a "container" view controller like the split view or navigation controller, yourself? Are you required to build the whole damn thing from scratch? I sense that you are, because seems to be hidden wiring in the interaction between view controllers. If so, thoughts on this?
I think the only hidden wiring in view controllers is setting parentViewController, which is required to support the categories declared for split and navigation.
View controllers are designed to be nested, with each controller owning a part of the view hierarchy. The only design goal is that no view controller reach into the view hierarchy of another controller. A parent view controller will usually have some call for adding child controllers so that it can set the frame of the view within the view hierarchy it owns. A child view controller should not do anything to the superview of the view it controls, as that is owned by another controller. Not should it set the center or frame of the view it controls.
For example, a navigation controller has a push method, in which it removes the previous controller view, adds the new controller view, and sets the frame of the newly added view. In general, a parent view controller is free to set the frame of the view of a child controller, but not the bounds.
If you want to change the animation of a navigation controller, I think you would start by implementing every method with an animated: argument. Set up your animation then call super with the animated flag off before committing the animation.
I haven't tried the multiple-view-controllers thing outside of the UIKit-provided ones (navigation/tab-bar/modal/etc) but I don't see why it shouldn't work. Under the hood, everything is a view, though I'll note that UIKit has special views for view controllers which no doubt have some kind of special handling by the system (UIViewController has a wrapper view, UINavigationController has a UINavigationTransitionView or something, ...).
I'd advise not worrying too much about "best practice" — just code something which does what you want. A couple of options:
Stick logic into view classes (ewwww!). One of our apps does this so it can handle rotation in a custom way (views slide in/out instead of rotating). We should've probably implemented our own view controller logic instead.
Break the model into components which correspond to views. Make each view know how to load its component and recursively load subcomponents. Then the view controller only needs to worry about "big picture" stuff.
Also note that you can load multiple nibs into the same view controller by e.g. connecting it to an outlet called editView.The big difference is that it's not done automatically by -[UIViewController loadView] so you need to do something like
-(EditView*)editView {
if (!editView) {
// Loads EditView into the outlet editView
[NSBundle loadNibNamed:#"EditView" owner:self];
}
return editView;
}
You'll also need to worry about adding it to your view hierarchy, unloading it on -(void)viewDidUnload (iPhone OS 3.0+), setting it up in -(void)viewDidLoad in case there was a memory warning during editing mode, etc...
It's not easy, but UI never is.
You need a master-detail view implemented with a split-view/popover-view and controlled with a UISplitViewController.
The master view is the document list and the detail view is the edit view. Each has its own controller. The two controllers themselves are managed by the UISplitViewController.
If you don't use the splitview controller you will just end up hand coding something that works very much like it. This is really the only way to do what you want easily in the API and it is the layout that iPad users will expect.
See Creating a Split View Interface in the iPad programming guide for details.
I have a view that contains a UITableView and a UILabel which works perfectly as far as I can tell. I really don't want to manage the UIView and UITableView with the same controller as the UITableViewController handles a lot of housekeeping and according to the documentation:
If the view to be managed is a
composite view in which a table view
is one of multiple subviews, you must
use a custom subclass of
UIViewController to manage the table
view (and other views). Do not use a
UITableViewController object because
this controller class sizes the table
view to fill the screen between the
navigation bar and the tab bar (if
either are present).
Why does Apple warn against using it and what will happen if I ignore this warning?
Update: Originally I quoted the following from the Apple Documentation:
You should not use view
controllers to manage views that fill
only a part of their window—that is,
only part of the area defined by the
application content rectangle. If you
want to have an interface composed of
several smaller views, embed them all
in a single root view and manage that
view with your view controller.
While this issue is probably related to why UITableViewController was designed to be fullscreen, it isn't exactly the same issue.
The major practical reason to use only one view controller per screen is because that is the only way to manage navigation.
For example, suppose you have screen that has two separate view controllers and you load it with the navigation controller. Which of the two view controllers do you push and how do you load and reference the second one? (Not to mention the overhead of coordinating the two separate controllers simultaneously.)
I don't think using a single custom controller is a big of a hassle as you think.
Remember, there is no need for the TableviewDataSource and the TableViewDelegate to be in the actual controller. The Apple templates just do that for convenience. You can put the methods implementing both protocol in one class or separate them each into there own class. Then you simply link them up with the table in your custom controller. That way, all the custom controller has to do is manage the frame of tableview itself. All the configuration and data management will be in separate and self-contained objects. The custom control can easily message them if you need data from the other UI elements.
This kind of flexibility, customization and encapsulation is why the delegate design pattern is used in the first place. You can customize the heck out of anything without having to create one monster class that does everything. Instead, you just pop in a delegate module and go.
Edit01: Response to comment
If I understand your layout correctly, your problem is that the UITableViewController is hardwired to set the table to fill the available view. Most of the time the tableview is the top view itself and that works. The main function of the UITableViewController is to position the table so if you're using a non-standard layout, you don't need it. You can just use a generic view controller and let the nib set the table's frame (or do it programmatically). Like I said, its easy to think that the delegate and datasource methods have to be in the controller but they don't. You should just get rid of the tableViewController all together because it serves no purpose in your particular design.
To me, the important detail in Apple's documentation is that they advise you not to use "view controllers [i.e., instances of UIViewController or its subclasses] to manage views that fill only a part of their window". There is nothing wrong with using several (custom) controllers for non-fullscreen views, they just should not be UIViewController objects.
UIViewController expects that its view takes up the entire screen and if it doesn't, you might get strange results. The view controller resizes the view to fit the window (minus navigation bars and toolbars) when it appears, it manages device orientation (which is hard to apply correctly if its view does not take up the entire screen) etc. So given how UIViewController works, I think there is merit to Apple's advice.
However, that doesn't mean that you can't write your own controller classes to manage your subviews. Besides the things I mentioned above, interacting with tab bar and navigation controllers, and receiving memory warnings, there isn't really much that UIViewController does. You could just write your custom controller class (subclassed from NSObject), instantiate it in your "normal" fullscreen view controller and let it handle the interaction with your view.
The only problem I see is the responder chain. A view controller is part of the responder chain so that touch events that your views don't handle get forwarded to the view controller. As I see it, there is no easy way to place your custom controller in the responder chain. I don't know if this is relevant for you. If you can manage interaction with your view with the target-action mechanism, it wouldn't matter.
I have an application where I did use 2 separate UIViewController subclasses below another view controller to manage a table view and a toolbar. It 'kind of' works, but I got myself into a massive pickle as a result and now realize that I should not be using UIViewController subclasses for the sub controllers because they contain behavior that I don't need and that gets in the way.
The sort of things that went wrong, tended to be:
Strange resizing of the views when coming back from sub navigation and geometry calculations being different between viewWillLoad and viewDidLoad etc.
Difficulty in handling low memory warnings when I freed the subview controllers when I shouldn't have done.
Its the expectation that UIViewController subclasses won't be used like this, and the way they handle events, using the navigation controller etc that made trying to use more than one UIViewController subclass for the same page tricky because you end up spending more time circumventing their behaviour in this context.
In my opinion, The Apple Way is to provide you the "one" solution. This served the end-users very well. No choice, no headache.
We are programmers and we want to and need to customize. However, in some cases, Apple still doesn't want us to do too many changes. For example, the height of tab bar, tool bar and nav bar, some default sizes of the UI components(table view), some default behaviors, etc.. And when designing a framework and a suite of APIs, they need to nail down some decisions. Even if it's a very good and flexible design, there is always one programmer in the world wants to do something different and find it difficult to achieve against the design.
In short, you want a table view and a label on the same screen, but they don't think so. :)