MVC and ViewController structure for iPhone "viewer" app - iphone

I'm creating a series of "book-like" apps and am trying to setup a template of sorts to be used across the series. I've decided against the UINavigationController approach, as it would seem to be too memory-intensive to have an accumulating stack of all pages and their assets.
I'm thinking of a simple RootViewController that manages the loading/destroying of Previous, Current and Next views. Does anyone know of a good template or example to start from for this basic skeleton? Preferably one with clear MVC separation?

There is a good example app "PageControl" by Apple which demonstrates this approach with the UIScrollView. I've used that code successfully in a project. I think it should be easy to adapt that way of handling the three views for a custom controller.

My Approach:
You could use the three controller (previousPageController,currentPageController,NextPageController) with UINavigationController rather then (As you said) having an accumulating stack of all pages and their assets,
If you have single controller like RootViewController for showing pages through three different views,Although you could go with this approach but you will end up having thousand like of code (could be :)) and that will require more maintenance, So It's better to have three different files responsible for pages rather then One.....
Thanks

Related

What is the best practice when using UIStoryboards?

Having used storyboards for a while now I have found them extremely useful however, they do have some limitations or at least unnatural ways of doing things. While it seems like a single storyboard should be used for your app, when you get to even a moderately sized application this presents several problems.
Working within teams is made more difficult as conflicts in Storyboards can be problematic to resolve (any tips with this would also be welcome)
The storyboard itself can become quite cluttered and unmanageable.
So my question is what are the best practices of use?
I have considered using a hybrid approach having logical tasks being split into separate storyboards, however this results in the UX flow being split between the code and the storyboard. To me this feels like the best way to create reusable actions such as login actions etc.
Also should I still consider a place for Xibs? This article has quite a good overview of many of the issues and it proposes that for scenes that only have one screen, xibs should be used in this case. Again this feels unusual to me with Apples support for instantiating unconnected scenes from a storyboard it would suggest that xibs won't have a place in the future but I could be wrong.
You are correct, breaking up the storyboards is the best way to go. Decomposition does more than just make parts of the UI more reusable. It also makes using storyboards in a team more manageable.
Lately, many of my storyboards have contained four or less scenes. It is easy enough for one person to solely build and maintain one or more of such UI modules. This practice reduces or eliminates merge conflicts.
In the case I do need something changed in a storyboard owned by someone else, I ask the owner first if he or she has any local changes. If so, I sometimes have the owner add the changes for me. Decomposition still requires some coordination, but it is substantially less than a full-app storyboard. Ever since I started this practice, I haven't had any merge difficulties.
As for XIBs, I don't think I wrote enough about them in my article. They are still very useful. They can be nice for single view controllers. However, this is not where they truly shine. XIBs have one advantage that storyboards may never have. The most basic unit of a XIB is a UIView, whereas the basic unit of a storyboard is a UIViewController. Since XIBs can hold collections of UIViews, they are great for visually creating custom controls. In a XIB, I can visually build a rotary dial or a GPS widget. Then I can drop these controls and widgets into storyboards or other XIBs. Such XIBs are seen more often in iPad apps since they have larger screens capable of holding many controls and widgets. It would be unnatural to build a UISwitch within in a UIViewController in a storyboard.
Now for the best news. It is possible to connect storyboards within Interface Builder and without writing any code. I was planning on releasing this technique after WWDC, since Apple may release similar functionality in iOS 6. However, since you asked, I decided to release it now. Rather than duplicate my explanations on how RBStoryboardLink works, you can find more details on my blog and on GitHub. This will make your UIStoryboard experiences much more enjoyable.
I found this article mentioned a lot of issues when using StoryBoard, one thing the author raised is using a huge of nib files in one StoryBoard, which I agreed he shouldn't do that, but there was other issues such as:
My root view controller has become a source view controller for lot of
segues and therefore its prepareForSegue: has become a stupidly large
method filled with a lot of “if (segue.identifier
isEqualToString:#”…”)” statements in a row
and
It is possible to assign view controllers in a storyboard an
identifier. Unfortunately this identifier property is not exposed in
the UIViewController class. This makes it very hard to perform safe
introspection of the view controller hierarchy at runtime. It would be
really nice if identifier was exposed for view controllers as well as
for segues.
and ...more other issues, I thought it does make sense, and I'm worry whether should or shouldn't use StoryBoard for now ??

Xcode 4 organization, Views and Controllers

Thank you for reading this.
These are my first steps in the iPhone Ipad app programming.
In order to learn from scratch (and because I know my app would need dynamic views), I decided not to use Interface Builder.
My question is(regarding the fact that I don't use IB): how would one use Views and Controllers?
I think I understand the MVC concept as it is repeated over and over again in the tutorials I follow, but after the "MVC explanation" part, nothing is made to make it clear "on the field" and closer to the real world (Earth being Xcode here).
Worse, sometimes it seems that some tutorials mix these two concepts up and use one word to say the other.
I read around here a lot of questions (and answers of course) based on the matter but I still don't get it. Sometimes it's too generic, sometimes it's too specific (for me at least).
For what I think I understood, the UIView is the static View when the View Controller is the logic which links the View to the data and those 3 concepts must be separated.
This separation, while a bit clearer with the use of Interface Builder seems to get quite blurry when you code everything as it becomes a virtual soup.
Technically, should I create a specific ".h" and ".m" file for each View AND ALSO for each associated Controller?
If I understand the MVC pattern, it's seems that I should but when I follow tutorials (without IB) it is never the case, view and controllers are created and manipulated within the same implementation files.
Any high level (I'm a noob, don't forget) but still applicable explanation of the use and best practices?
Let's say I want to create a simple app with a green view I can swipe to get to a red view.
I know for sure that I would need at least an:
xxxappDelegate.h
xxxappDelegate.m
xxxView.h
xxxView.m
What else?
1)Where should I put the the second view (along with the first one in "xxxView" or should I create another class h and m file?)?
2) What would the controller(s) do, for that kind of application? In which files would they be created and in which files would they be invoked and how would they "control" the related view?
3) Mainly, regarding to MVC pattern and the fact that there would be no IB, how would you organize that app?
I know it's a lot if you go into the details and code but that's not the point here.
Thank you. This - as simple as it seems - would be of a great help and is not as easily found in tutorials as you might think.
I understand the tutorials I read but they are so particular. As soon as I try to create something on my own which is not a "Hello World" screen, I realize that something is missing, logic wise.
Thank you very much for your help.
Sorry, but I can't get past your first paragraph. If you don't use Interface Builder, you are not going to be a successful iOS programmer. It's that simple. The best advice I've ever read about this is in this Aaron Hillegass interview:
Experienced Cocoa programmers put a lot of the smarts of their application in the NIB file. As a result, their project has a lot less code. Programmers who have spent a few years working in Visual Studio get freaked out. They ask me stuff like, "Can I write Cocoa apps without using Interface Builder? I like to see the code. Maybe I can just explicitly create my windows and the views that go on it?"
It is difficult to explain how the NIB file (and a few other scary ideas) create leverage. It is that leverage that enables one guy in his basement to compete with a team of engineers at Microsoft or Adobe. It is like I showed a chain saw to a early American colonist, and he said, "Can I cut down the tree without starting the engine? I don't like the noise. Maybe I can just bang it against the tree?"
Yes, it's hard to generalize after reading specific tutorials, but you will learn. I thought the learning curve was insurmountable when I first started, but if I can become a programmer that gets paid to write Cocoa software, you can too. Just keep reading and practicing. Don't fight the tools--use them.
Early:
In order to learn from scratch (and because I know my app would need
dynamic views), I decided not to use Interface Builder.
Later:
As soon as I try to create something on my own which is not a "Hello
World" screen, I realize that something is missing, logic wise.
I think what is missing logic wise is that you have accepted your assumption that Interface Builder was a crutch and that to learn "from scratch" you had to avoid using it. You are trying to learn the MVC design pattern but you are not willing to use the tools that have been designed to support it.
In Apple's own documentation they discuss the fact that sometimes there is value in having combined roles—Model Controllers and View Controllers—and that is worth reading, as it may explain some of the code examples you're reviewing. But my primary advice would be: before assuming you know better than the people who built the tools, trying using them the way they recommend. It might be an eye-opener.
Additions later:
OK, so to try and actually answer your questions...
1)Where should I put the the second view (along with the first one in
"xxxView" or should I create another class h and m file?)?
If I am understanding correctly and the two views you are thinking of here are the red and the blue displays to the user, you wouldn't have a second view—what you would do, whether in IB or in code—is to have an element in your view on which you changed a colour property... This would be done programmatically whether you were setting up the parent view in IB or in code.
2) What would the controller(s) do, for that kind of application? In
which files would they be created and in which files would they be
invoked and how would they "control" the related view?
There would be a view controller that would implement the gesture support, and would provide a method for changing the colour of the item in the view between blue and red when that swipe gesture was successfully received. I would have a ViewController.h and and ViewController.m. I think if you were implementing the View entirely in code, it would be implemented in the ViewController.m rather than having a separate View.m. (If you were using IB, you would have a ViewController.h, ViewController.m and ViewController.xib, with the latter providing the basic setup of the view elements and layers.)
You would create a ViewController instance in your AppDelegate.
3) Mainly, regarding to MVC pattern and the fact that there would be
no IB, how would you organize that app?
As above.
If you really insist on going without IB (and I agree 100% with SSteve) then in addition to the files you list you will also want to use a UIViewController. Now, it is important to know that you only need to create header and implementation files when you are adding or changing default behavior.
In you case, the view can probably just be a generic UIView, so you wouldn't need the files. What you would do is subclass UIViewController, and put the swipe logic there. In the swipe logic code you would probably just change the background color of the view.
You would instantiate the view controller in the delegate (in this case anyway) and create the view in the view controller's loadView method. That is required since you won't be using IB.
Personally though, I think that IB does a great job of encouraging proper MVC patterns, and if you are just starting then you should go with IB.
In practice you mostly do not make classes for views, unless they need to do custom drawing or display.
For lightweight configuration of views, that is often done in the viewController's viewDidLoad (or I guess in your case loadView) method.
Yes it's a good idea to keep model and view separated, but that's also balanced with the equally good idea to reduce the amount of code that exists. The less code that is written, the fewer bugs you will have.
Since you are just starting out at this point I would absolutely start by using ARC, and using IB - even though I'm sure you're tired of hearing that from everyone, I'll give you an alternate take. Less code means fewer bugs. And the fact that so many experienced developers are telling you to use it should be a giant clue about what a productive path forward is. I mean, are you doing this to build applications or learn every corner of the UIView class?
To speak to your code example, you do not need the UIView custom class. Just create use a UIViewController's main view as a container view, place a UIView inside with the background set to red. On swipe (using a gesture recognizer attached to the container view) call the UIVew method to swap in a new green-background UIView for the existing red view, you can even define the transition style.
Or create a scroll view in the container view, set up the red and green view inside the scroll view, set the content size and enable paging on the scrollview.
Or create a custom UIView class as you had, listen for touch events and slowly adjust two subview positions to follow the drag action.
Or use an OpenGL backed view, and based on the gesture recognizer pan the scene you are observing with two triangles for a green rectangle and two triangles for a red rectangle.

How mvc pattern is implemented in iOS user interface? (view-based XCode temlpate)

I'm new to iphone development. There's a lot of books on this topic available. But most of the beginner's guides are mostly concerned with Interface Builder usage and lack the information about existing built in XCode code templates or something that could help me in understanding MVC implementation in code. I found that it is possible to write working iOS program without ViewController at all. Well, it seems to me like that after working with the sample code called ViewTransitions.
So, the question is - why is that possible to avoid ViewController implementation in a program that has an interface with a button? If the answer is going to be too long, could you please recommend kind of tutorial or manual covering this topic.
Thanks in advance.
#user697562's answer is essentially correct: in the case of ViewTransitions, the role of the controller is played by the app delegate. The app does next to nothing -- it just switches betweeen two views to demonstrate several possible transition effects -- so a UIViewController isn't really needed there.
Notice that there's also nothing in ViewTransitions that you could really call a model object. If you're looking for a strong example of MVC, ViewTransitions isn't the best project to look at. Other sample projects, such as TheElements, give a better demonstration of MVC in action.
There is a concept called delegation. A concept which helps maintain MVC. It helps to keep the model separate from controllers. For eg: - UITableView/UICollectionView , which knows how to display the data and other ui stuff.
But it does not know which cell to display or what data to display at a particular index. And this is where delegation and the delegate object comes into place. UICollectionView handles all the view part whereas all the non view part is handled by the delgate object, which gives the required data for the view. This way a delegate(usually a separate view controller) acts as a data source and UICollectionView as a ui renderer.
in ViewTransitions, there IS an App Delegate, which is kind of your sole "controller". Even ViewTransitions has:
transition.delegate = self;
IOS is a bit different from some frameworks in that you aren't as "in control" of what is going on. It often uses a delegation model where you set your code as the delegate, but it (IOS) is in control. Still, you can write in MVC style, it's just your "C" isn't fully in charge.

IPAD APP Design Question - Lots of pages, with little to do

I am new to IPhone/iPad development and have a application design question.
1) I have about 60 different pages I converting from a Flash file. They are largely pretty devoid of stuff to do. Mainly reading and and some images.
2) There are a few interactive things (buttons, animations,etc.) on on about 50% of the pages
My initial thinking is to use a navigation controller (hidden, as I don't want as part of my design) to use the push and pop functionality. Each page would have it's own viewcontroller.
My other thought was to use hidden UINavigationController, but to group pages in specific areas and have multiple NIB files read from one view controller.
Is one better that the other? Or have more advantages than the other? Or is there a better way?
Not sure how to answer this, but you could probably have a few NIBs and ViewControllers and reuse them. There are a million ways to do simple navigation without UINavigationController -- it might be more of a pain that not using it.
For example, is navigation always like a tree (forward, forward, forward, back, back, back) --- or could it be more free form around a graph?
If navigation is simply push and pop, then use it, but try to keep the number of different viewcontrollers/NIBs to a minimum (for maintenance purposes)
The usual recommendation is one view controller per full page of content. However, if your content is remarkably similar, reusing the view controller is valid. Before proceeding, I'd think carefully about your navigation model:
Will users be able to jump from any page to another (say like a magazine)?
Do some pages require the user to visit other pages first?
For (2), the push/pop model works quite well, whereas for (1) the push/pop model of a UINavigationController may be too much trouble.
So focus on your presentation, and then let the code follow from that.

App development: Always subclass, always load from NIBs - caveats?

This is Cocoa Touch (et al), iPhone, XCode only.
After completing my first commercial iPhone app, I'm struggling a bit to find a way to start and expand an app from scratch which gives the most linear development (i.e., the least scrapping, re-write or re-organization of code, classes and resources) as app specs change and I learn more (mostly about what Cocoa Touch and other classes and components are designed to be capable of and the limitation of their customization).
So. File, New Project. Blank window based app? Create the controllers I need, with .xib if necessary, so I can localize them and do changes requested by the customer in IB? And then always subclass each class except those extremely unlikely to be customized? (I mean framework classes such as UIButton, CLLocation etc here.)
The question is a generic 'approach' type question, so I'll be happy to listen to handy dev practices you've found paid off. Do you have any tips for which 're-usable components' you've found have become very useful in subsequent projects?
Clients often describe programs in terms of 'first, this screen appears, and then you can click this button and on the new screen you can select... (and so on)' terms. Are there any good guides to go from there to vital early-stage app construction choices, i.e. 'functions-features-visuals description to open-ended-app-architecture'?
For example, in my app I went from NavBar, to Toolbar with items, to Toolbar with two custom subviews in order to accommodate the functions-features-visuals description. Maybe you have also done such a thing and have some advice to offer?
I'm also looking for open-ended approaches to sharing large ("loaded data") objects, or even simple booleans, between controllers and invoking methods in another controller, specifically starting processes such as animation and loading (example: trigger a load from a URL in the second tab viewcontroller after making sure an animation has been started in the first tab viewcontroller), as these two features apply to the app architecture building approach you advocate.
Any handy pointers appreciated. Thanks guys.
Closing this up as there's no single correct answer and was more suitable for the other forum, had I known it existed when I asked :)
If you want to know the method I ended up with, it's basically this:
Window-based blank app
Navigation Controller controls all, whether I need to or not (hide when not used)
Tab Bar Controller if necessary
Connect everything <-- unhelpful, I know.
Set up and check autorotation, it might get added to some view later.
Add one viewcontroller with xib for each view, you never know when they want an extra button somewhere. It's easier to copy code than make the max ultra superdynamic adjustable tableviewcontroller that does all list-navigation, etc.
Re-use a viewcontroller only when just the content differs in it, such as a detail viewcontroller.
Minimize code in each viewcontroller by writing functions and methods and shove them in a shared .m
Everything that's shared ends up in the App delegate, except subclassed stuff.
Modal viewcontrollers are always dynamically created and never have an xib.