I am new to Objective-c, I want to ask what is the different between view controller and view such as "UITableView" and "UITableViewController"?
What happen if I use UITableView instead of UITableViewController?
Thanks
You should look up the Model-View-Controller pattern in the Apple's documentation, since it is very important for using Cocoa. Basically, the idea in Model-View-Controller is a pattern for designing your class structure. Broadly, the model is where the application's data should be kept. The view is what controls the application's appearance and the controller is the place where the two are assembled. (Ideally, the view and the model classes do not even need to know about the other's existence).
Hence, the UITableView and UITableViewController are two different classes with two different purposes. The UITableView controls the appearance of the data and the UITableViewController "controls" the view (generally by passing it the correct data for display and layout). Since this pattern shows up again and again in Cocoa programming, you should take some time to become familiar with it.
They are two different things, they cannot be substituted for the other.
iOS follows the MVC design pattern, which stands for Model-View-Controller. The two classes you mention are 2 pieces of the overall puzzle.
The View is what gets displayed on the screen. That is its responsibility. So, the TableView is responsible for telling the phone what to render on the screen.
The View is also accompanied by the Controller. The controller decides what to do when something happens (user interaction, and other events that can happen at any time). So, the TableViewController is responsible for making the table do stuff (for example, telling the TableView what data to use for displaying on the screen).
So to sum it up, they are completely different, but they work very closely together in your application (you will almost always have 1 Controller for each View.
Well, the short answer is that one is the View and one is the Controller. Combine this with your data (the Model) and you have all the parts of MVC (Model - View - Controller).
Think of it this way, the UITableViewController controls the UITableview. They are complementary and they need each other to work.
Related
I have a simple project that was started from a Master/Detail template for iOS7.
I'd like to layout the detail view controller just like iOS settings. Do folks recommend using a table for that or just laying out the controls one by one?
Here is a screenshot of the effect I am looking for:
This is probably a matter of taste/opinion but I prefer tables for this kind of thing for these reasons:
You get all the nice features of tables right out of the box (efficient scrolling, cell reuse and delegate methods to handle where to push new view controllers on to the stack, etc...).
Flexible data model backed cell data. Your table view needs to be backed by some "settings" model object collection, obviously. That collection can be modified to include or exclude settings programmatically. Combine this with custom cells and you're off and rolling. This is really nice if your UI needs to change on the fly.
Code Reuse. If you have another set of "settings" you can use this data-backed table view approach and change only your data model. Doing this manually means you have a new view controller for every settings view. In your example picture, I'd bet my lunch that the 3 view controllers you see in that image are the same type of object.
The table's delegate methods are really helpful when segueing or pushing to new view controllers. Imagine having 10 settings that all took you to separate view controllers. You'd have to manually hook those transitions one by one, yuck.
Of course if you only have 1-2 settings that will never change, perhaps manual is the way to go. For my money, though, tables make sense because things like this always seem to change.
I am making an app that has about 20 different view controllers that are loaded into a single container view. Some of the views have sliders and buttons and some have only buttons.
Is there a strategy I can use to make building the views controllers more inline with Objective C coding techniques?
Currently I am trying to combine similar methods into model objects but before I get too involved I thought I'd ask if there is a better way. I'm also willing to do the groundwork and research so any keywords to point me in the right direction would help, i.e. protocols, delegates, etc.
The main piece of advice I'd give you is to consider whether or not each one of those view objects needs to be controlled at all. Consider UIViewController like the delegate between the view and the model. If you don't need an extreme context switch (i.e. pushing a new view onto the navigation stack), then is it really advisable to have 20 delegates floating around? In most cases, not really. UIViewController is not a "heavy object" by any stretch of the imagination, but it can quickly make your codebase unwieldy and large if every time you decide to throw a new component onto the screen, you subclass UIViewController.
Try to focus your attention on dividing the logic to setup the view and the actual responsibilities of the controller (reacting to model changes, dispatching operations, updating the view) into a UIView subclass and a UIViewController subclass respectively. If you truly do need to keep some component of the view separate because its logic simply cannot fit under the main view controller's category of responsibilities, then, and only then, is a new view controller appropriate.
When I am programming a universal app, lets say I have an IBAction like so:
(IBAction)magicCode:(id)sender {
textField1.text = "TEST";
}
Do I need to create a new IBAction for each view (iPad and iPhone). I can't have textField1 twice in header file, so I am just wondering how everyone else does this. Do I need to put a textfield in the iPhone app with a different name than the one in the iPad app? Or is there some other way everyone else is doing this?
Do I need to create a new IBAction for each view (iPad and iPhone).
First, actions are typically included in view controllers, not views. I think that's probably what you meant, but I point out the difference because I've seen a lot of people get confused on this point.
When you're creating a universal app, i.e. a single app that adapts its UI to the device (iPad or iPhone/iPod Touch) on which it's running, a common strategy is to provide different view layouts that make the best use of the available screen size, but to use the same view controllers. So, for example, say you have an app with a master/detail interface. On small devices, you'd present the master part of the interface first, and when the user chooses something you'd display the detail part of the interface. On an iPad, with it's larger screen, you'd display both master and detail interfaces simultaneously in a split view. Comparing the two, the views are likely to be different, and the way the view controllers are presented is different, but the view controllers themselves should stay the same. This is a good thing, since much of the work of creating an app goes into creating the view controllers.
If your app is similar to what I've described (or if you can make it similar), then no, you don't need separate actions for iPad and iPhone because you'll be using the same view controllers in both cases. There may be times, though, when the behavior of the app on the two different devices is different enough that it makes sense to have iPad-specific and iPhone-specific view controllers. You might still be able to use the same actions by deriving each of those from a common parent class that contains the actions. If not, you'll need to have each class implement its own actions.
No, you can have the same IBAction and IBOutlet in a UIViewController dealing with textfields in two different Nibs (one for iPhone and one for iPad). That's the whole point of separation between View Controller and Views in MVC architecture.
Just use the same UIViewController as File's Owner in both the Nibs and make all the appropriate IBOutlet and IBAction connections and everything will work.
I'm just getting into desktop Cocoa development (I have experience with iOS development). If this question seems basic, forgive me.
That being said, I'm dealing with a large program with lots of calculations and functionality to deal with. There are almost a dozen views, organized with an NSTabView. Rather than dumping everything into one monstrosity of a class and creating a XIB file that brings my system to its knees (Xcode apparently isn't that efficient…who knew? :P). I'd like for each tab to be its own NSViewController with accompanying XIB; as such, I'd like to load each tab's view from the corresponding XIB.
I'm thinking of this in terms of UITabBarController, but this doesn't seem to work (there isn't an NSTabViewController as far as I could find). I'm not sure how to do this (or even if it's possible—but I can't be the only one with this issue?), and I'd appreciate any assistance. Thanks!
Update: I tried assigning the controller's view to the tab's view, but quickly realized that wouldn't get me anywhere. Is it worth creating an NSTabViewController from scratch, or is there a solution out there?
Cocoa development on the desktop has some major differences compared to iOS development. One of them is the use of view controllers - they aren't strictly necessary - and when you use them you can just stick to a generic NSViewController regardless of what kind of view it contains. All of the methods you need to control the tab view are in the NSTabView class - not the controller.
Having said that, putting 12 views in to a tabview sounds like a painful way to interact with a program. Have you thought about a source-detail type setup (think itunes or mail with their sidebars - each entry in the sidebar corresponds to a different view)?
I've ditched the tab bar, and as per sosborn's suggestion, I have used a split view—or rather I've put a table view on the side, and a custom view taking up most of the screen. Then, in my AppDelegate, I have individual controllers as ivars (I need individual controllers because there are a lot of calculations involved, and I don't want to have a monster class handling them all). They'll be lazily loaded, and the view will be assigned to the current controller's view as necessary.
I am writing a fairly complex iPad app - my first bigger one.
This app has some custom UIViews that present fairly complex data, including a table. These views do not take up the whole screen, and there can (and likely will) be many of them on screen at any time (though only one would be in an "expanded" state where the table is shown).
Here's a basic example that should convey the basic principle:
Please note that these things are not supposed to be in popovers; instead, the FamilyViews expand to show their detailed data. (And please also note that this mockup was only created for the sake of this question and has little to do with how my interface is going to look; I know this is not good screen design)
I'm undecided on who to put as the delegate and datasource of these custom views:
Making the ViewController for the current screen delegate and datasource is unelegant, because it's not just one table that's part of the VC's main view.
Making the View itself the delegate and datasource seems a bit weird to me because it feels like giving the view too active a role; making it into a half-controller.
Making the underlying model object the datasource seems too tightly coupled, and also breaks MVC. And it doesn't answer the question of who should be the delegate.
I'm tending towards making each of these "FamilyViews" delegate and datasource for their own tables. Action on these tables will have to be coupled to the FamilyView's delegate (the ViewController), but that shouldn't be a problem, should it?
Anyone have some input on this?
Views should know how to paint themselves and layout their sub views, depending on their properties, and that's it.
You definitely should let a controller class be the delegate instead of the view itself.
The delegate controller doesn't have to be the view controller that displays the view, though. It could easily be a completely separate controller class that only knows how to handle what the view requires.