This is more of a philosophical question than anything, so give me your thoughts.
The iPhone SDK documentation specifies that you may have a tab bar controller contain a navigation controller, but you can't have a navigation controller contain a tab bar controller. It seems that there are times when you might want to organize views within a view that is part of a navigation controller stack in a tabular fashion. Is this unreasonable?
I accept what Apple dictates in these areas as gospel as the HIG does provide best practices that seem to reveal the path of least resistance (I'm sure there are exceptions to that). In the tab bar case, however, I'm not sure the design reasoning behind it. Maybe it's obvious to others, but I can't think of a good reason why you wouldn't allow tabs as anything but a root level view controller.
What do you all think/know? What design flaw would this create? How would you solve this problem of wanting a tabular presentation of views within a view? Do I need to re-think the entire design?
Thanks.
I can see where they are coming from, from a design perspective. Tabbars feel anchored, constant, where navbars feel dynamic and mutable. So a tab containing dynamic content makes sense, whereas a single spot in the dynamic hierarchy of a navigation stack containing a tab bar, anchored to the bottom of the screen doesn't feel as right. The Three20 implementation does handle this in a way that makes more sense, anchoring the tabs underneath the nav bar, so that they feel more like they are part of that spot in the navigation stack.
Having said that, Tweetie rolls it's own tab bar, if I remember correctly, without a UITabbarController to circumvent this detail in the UI guidelines, and it totally works from an interaction perspective.
The short answer is it would be confusing to the user to allow UITabBars inside a nav controller. The app would certainly not behave as most users would expect. But, that's just UITabBar, not the design concept of tabs in general. Tabs inside a nav controller, should, in my design opinion, go at the top, not the bottom, as does a UITabBar.
There are a few different ways to do this.
I've done "tabs" inside a navigator view controller by having the first row in a table view have a segmented picker. (See the HangTime app on the app store). I think it works pretty well, but they aren't really "tabs".
Joe Hewitt, the guy who wrote the Facebook app, solved this problem by creating his own "tab bar" view and controller, although it's rendered quite differently than a UITabBar. That element is available through the Three20 framework, and open source library. Check it out:
http://github.com/joehewitt/three20/tree/master
I think the tab bar controller is intended to be the main point of navigation around an app if it's used. If a nav controller contains a tab controller, then the tabs will switch whenever you navigate elsewhere, which may be confusing to users who are used to using them the regular way in other apps. I think its a cool idea however, but apple may not feel the same way.
Related
I am making an app that has both a bottom bar and a top bar (both are customized) and i want them to stay there the entire length of the app while the middle portion switches between views. But the kicker is at some points in the app, i want to have the top bar and bottom bar slide off the screen and be able to be dragged back on.
What i was thinking was to have one main UIViewController with three UIViews (top bar, middle section, and bottom bar) each running code from their own respective files. Sort of like how a Tab bar works with a nav controller. or do i have that backwards? i dont really know... but any constructive advice helps =)
Im fairly new to xcode and i've been trying to find a way for a few days now, so please dont be too harsh on me. Thanks!
In general, we build one view controller for each 'screenful' of content. So the basic advice for you would be to make the app in a way where each 'section' is it's own view controller. This is especially important to the MVC paradigm, where your business logic should be in the viewControllers, not the views (just display and interaction logic there). If you had just one view controller, it would get convoluted FAST by trying to manage multiple sections.
A good route may be this: Embed the whole hierarchy in a navigation controller, which gives you the top bar. Then make a custom view controller class which knows how to make your bottom bar, and have each section subclass that.
The side effect is that the bottom bar will be uniquely created for each section VC. If that is not desirable for you, you can explore view controller 'containment'. It is basically a technique for building components like the navigation controller, which keep certain elements onscreen for a long time, while exchanging 'content' view controllers for a smaller portion of the screen. It's not the easiest thing to do, and should be considered carefully. However, if you really need to keep the same instance of something on screen while other view controllers come and go, it may be the right way to go. That said, consider the other idea first (each section manages it's own bottom bar). You can accomplish it in a way that promotes code re-use, etc.
I'm building an iPhone app and I'm sort of confused about which approach should I choose for views and controllers.
I would like to have a tabbar at the bottom with three options. I would also like to have a main view displayed when the app shows (along with the tabbar) but I don't want this view to be part of the tabbar options.
So, when the app begins, the tabbar has no option selected but the main view displayed. When a tabbar options is selected, in its top bar it should display a back button to the main view. When the back button is pressed, the main view display again with no tabbar option selected.
Which approach should I choose?
Hope it makes sense.
Thanks.
I understand what you're trying to do, but you shouldn't do that. I don't like that design at all. You should have one navigation controller for each tab.
You should probably read Apple's Human Interface Guidelines as it's possible they would reject your App if they thought such an implementation with a TabBarController was confusing.
As an alternative, you could possibly have the "main view" as you call it accessible with a button in the Navigation bar at the top and then add that to all three tabs. Not necessarily a better design but you probably wouldn't be breaking the guidelines.
A better alternative might be to use a UIToolBar at the bottom instead of the Tab bar which has the three buttons spawning your views modally which can then be dismissed as you suggest.
Remember though, your App's users have built up a knowledge of how App's are generally supposed to navigate, feel and control so you should think carefully before deciding to go against that.
Firstly, I think you should reconsider giving your Main View it's own tab. That way it's a no-brainer for the user to return to that screen. BUT, if you STILL don't like that idea, read on...
The UITabBarController has the unfortunate side effect of not being able to be removed once created (even if you delay it's creation by instantiating it programmatically).
SO...
Option 1: Make your MainView a modalPresentation sub-view, displaying it ON TOP of one of the views in your tab bar (hiding the tabs until you're ready to show them again).
Option 2: Give a subview of your first tab a...
mySubViewController.hidesBottomBarWhenPushed=YES;
This will make the UITabBarController disappear temporarily (just on that view, until you're ready to show the tabs again).
Both options seem kinda messy to me, but they are possible. Depends on how well you execute them, I suppose.
Hope this helps!
You could add the main view as another tab.
OR
You present the main view modally when the app starts over the tab bar views.
The first option would be used more if the view holds the same kind of content as the tabs, for example if the app was an online store, the tabs would be Categories, Search and Recently Added, with what you call the "main view" being the Home page (showing offers or something). (So all the views/tabs would be showing products on the store)
The second option would be more if the content of the main view is different to the tabs.
Keeping with the online store example, if the tabs were Categories, Search and Recently added and what you call the "main view" being a login/logout screen. (so the tabs would be showing products, but the modal view ("main view") being more admin related, and it's main purpose not being to display products.
I've put together an app that uses a table view and navigation controller to display a list of documents (HTML docs) and by clicking on a document title will open up a detail view and display its contents. That works a treat but it will ultimately be part of a bigger app which will have a menu of which this would be just one of the options.
I've done a lot of digging around but am still unsure on the best approach to take for building the overall app. A lot of advice seems to be to use the navigation based application template and push out the menu view and hide the navigation bar but is this really the recommended way to go?
I've read the Apple docs and Modal View controllers sounds like they could be and option but I am then unsure how I would slot in my existing RootViewController etc?
Really appreciate someone taking the time to help get me on the right track
Cheers
Kieron
Using a navigation controller is a very common way of structuring this. And as you note, the nav bar itself can be hidden on some view controllers.
Be careful about presenting view controllers modally -- Apple's advice in the HIG is to use modals when you are focusing the user's attention on a certain piece of information or a crucial task -- don't just use them willy-nilly.
hi
I'm new to objective-c
i need to create a view, that has four buttons at the bottom, and a view above them that changes according to which button you press.
now i've been reading a bit of tutorials, and i still have difficulties understanding the different nib files.
But i'm wondering.
i have 'tab bar controllers' in the controllers sections in the library and i have 'tab bar' in the 'windows views and bars' section.
now according to what i've read, and understood...
i have to use tab bar controller and add it to the 'Mainwindow.xib' and implement and link the stuff.
But can't i just add a tab bar in my 'appnameViewController.xib', and manage the tabbar items' click to change views. without relying on the tb controller??
If you want tab bar functionality you really should use UITabBarController. While it is possible to repsond to the the taps on the tap bar and switching views by yourself it is not recommended. Some reasons why:
You would just duplicate code that UITabBarController already does.
UITabBarController will handle things like unloading views not on screen when a memory warning is received.
If you end up changing the amount of tabs in your application it would still just work with a UITabBarController.
There are probably many more better reasons but since an iOS device have limited memory the memory aspect alone would make it a no brainer.
You need to familiarize yourself with the Model-View-Controller design pattern, which Cocoa follows religiously. Controllers deal with the application-specific logic the user interface (the views) provides.
For example, a button is a view but a controller handles the button's click (and setting its enabled/disabled state, etc.) depending on application logic.
I think you are confusing the tab bar view with it's view controller (UITabBarController).
Apple's documentation explains it well:
http://developer.apple.com/library/ios/featuredarticles/ViewControllerPGforiPhoneOS/TabBarControllers/TabBarControllers.html
I'm tryin to grasp the fundamentals of Cocoa (Iphone) MVC design, but it's being quite tough. I've come accross several example applications, from the web, books.. but I've found nothing related to what I'm searching, since most of the examples just present a simple app (ie, a viewcontroller with a flipside viewcontr and a bit more..). So let's see if someone is willing to help me out in pointing me to the right direction:
My goal is to build a somewhat complex app. I'd like to have the following relation of views:
Presentation view (which would have a controller loading several memory intensive vars)
Main menu view: different options that would result in entirely new complex views. In example, a Begin option to initiate whatever the app permits to do; a second option to do another complex task with different views and actions within it, an Options option to configure options; a help option, an about option, etcetera..
In a first approach I tried to embed several rounded buttons in a view under the MainWindow nib with an associated app delegate. This approach though posed the question to how I manage to switch between views/viewcontrollers. After having uncaught exceptions because I probably don't fully understand the basics, I tried to move on to more 'simple' things.
Then I came accross the Navigation and Tabbar default Cocoa controllers. I don't want a tabbar, although it could come well for other parts of this app. Then the nav controller is what I think is most suitable for this case.
Thus, am I on the right spot if I build a hierarchichal app where its root is a nav controller? I've seen I can customize the main view to display a customized table, where each cell coud act as a button to spawn its respective view+viewcontroller. From here then I can keep building the 'leaf nodes' of this hierarchy of views/viewcontrollers, right? Eventhough I don't like the animation that by default provides the nav controller, I assume I can get rid off it..
So to sum it up in an easy way: I'd like to obtain a menu like those that can usually be seen on Cocos2d apps.
It's frustrating to ask this, I know it has to be easy but I find the documentation quite a mess aswell as the examples I've seen.. GUI programming it's being a tough learning curve :/
Thank you for any answers in advance, and excuse me for this long post.
Thus, am I on the right spot if I
build a hierarchichal app where its
root is a nav controller?
Almost. A nav controller (despite being a subclass of UIViewController) does not control views but rather other view controllers. The nav controller pushes and pops the view controllers which in turn causes the controller's respective views to load and become visible.
Therefore, the "root view" is actually the view that is controlled by the view controller that is in the nav controller topViewController property.
The app delegate serves to hold the nav controller and to tell it which view controller to push on the stack first. After that, the view controllers tell the nav controller when to push and pop them.
Otherwise, you're on the right track. You should always attempt to present information on a mobile platform in an hierarchal manner starting with the most general at the top and growing more specific as you drill down.
And you shouldn't be embarrassed at finding this confusing. 90% of the introductory/tutorial info out there, including books and Apple resources, focus on the gee whiz aspects of the interface and tell you next to nothing about the actual application design or how all the parts fit together conceptually.
You right about how little information is covered about app delegates to nav controllers. I been digging and trying to get all my screens linking etc. Having alot of fun watching my apps start to look more then just some Frankenstein monster UI. ahahah
The Itunes dev videos are great for looking at push and pop stack UIviews theory. I found they moved a little fast but after watching them the hands did make more sense. I have been forcing myself to watch them all and get a really good feel for whats going on. Hopefully have a nice app working soon.