I have a fairly simple iPhone application that I want to have run on both the iPhone and the iPad. I'd like to just have the iPad version be a bigger version of the iPhone version, scaled up or not -- I'm working on an iPad-specific version of the app that makes better use of the interface, but wanted to make sure my existing customers have something in the meantime.
The app is a simple tab-based application, and within each tab is a navigation controller that presents a table view, each of which can drill down a couple of layers. Everything mostly works -- I have a couple of instances of views not filling the space available, but I can fix that. My biggest problem right now is that the navigation controllers universally break when I try using them. Once I drill down a level or two, I suddenly won't be able to come back up again.
Let me try to explain in more detail:
One tab starts off with a "year" table view, showing all years that have entries; if you tap a year, it pushes another table view with all months in that year that have entries; if you tap a month, it pushes another table view that shows the individual entries; if you tap an entry, it pushes a view (a UIWebView, with some extra widgets) that shows an entry's details.
Each push is done with [self.navigationController pushViewController: foo animated: YES]. The three table view controllers I mentioned above are all created from the same nib (in fact, everything pushed onto a navigation controller in any tab is loaded from the same nib). Since I know there are only up to three levels of navigation, I just allocated three identical view controllers and use one, two, or three depending on how many entries there are.
Popping these controllers off using the "back" button seems to universally mess up the state of the view controller. So, if I drill down to the third view -- showing everything in a single month -- I won't be able to pop all the way back up to the first view: the back button stops working if I pop up one level.
Another example in another tab: it's one table view that you can tap any entry on, and a new view controller will be pushed that shows the details of that entry. If I tap an entry, tap the back button, then tap the entry again, no back button appears, or sometimes, the text that would go inside the back button appears, but no button appears!
This behavior happens if I try running the iPhone app in scaled mode (built with base SDK 4.0, supporting OS 3.2) or in native mode (built with base SDK 3.2). It runs without problems on the iPhone. I'm kind of at a loss here, because this stuff always "just worked" out of the box, mostly from the defaults that were set up back when I first created the project.
My programmer's instincts are telling me that I'm doing something very wrong in my view navigation, and that the iPad is just exposing it, but I can't figure out what it is.
Has anyone run into an issue like this, or suggest something it might be or some better way to debug what's going on?
The issue was that I had a category on NSMutableArray, which added stack-like methods push and pop. Removing this category class fixed this issue.
WTF, though.
Related
Hy everybody
I am a newbie ios programmer and I'm facing many doubts when I must switch the pages of my app.
With the term "page" I mean a UIView that fills the whole screen with some widgets (buttons, textboxes. tables..)
As far as I have understood what I've read I should use an UIViewController to manage each of these pages
since each page should be a screen’s worth of content.
My App starts with a ViewScroller with many buttons and when the user clicks one of these it opens a new page.
The first page is the UIView connected to the RootController Of the Window.
So far to open the new pages I add a child controller to the RootController and it's view as a child of the view of the RootController:
RicLocaliController = [[RicercaLocaliViewController alloc] initWithNibName:#"RicercaLocaliViewController" bundle:nil];
[self addChildViewController:RicLocaliController];
[RicLocaliController didMoveToParentViewController:self];
[self.view addSubview:RicLocaliController.view];
RicLocaliController.view.frame = self.view.bounds;
When the user clicks the "Back" Button I remove the child controller and the child view.
Going down this road I would get a dynamic tree of Controllers with their Views.
So far I have not encountered problems and my app can go up to a third level in the tree and come back. Each page behaves correctly when orientation changes.
But I'm afraid that adding, for each subpage, a child controller and a child view could be not the right thing to do.
I'm afraid that if I nest a lot of pages when the orientation changes the app could respond slowly since also the superviews will do something to manage this event.
So what I wonder is if what I am doing is completely senseless, if I should use Navigation controllers or some other way to manage my page changes.
Unfortunately my boss is not giving me enough time to study well the subject and so I would like an advice to follow the best solution possibly using the most standard and less complex component offered by the framework instead of the newest features.
I read a lot of web pages on the subject but it seems to me that there are many ways to manage the navigation beetwen pages and this makes me confused.
I apologize for my bad english but i'm tired and English it's not my first language.
You HAVE to do some studying. You will spend more time clearing up all your problems later otherwise... but, here are some tips.
Using nested ViewControllers leads to all kinds of trouble so if you are short of time, skip that.
Think of each "Page" as one ViewController. A ViewController has a property called View but that is actually just the top view of a whole hierarchy of views. A view is the base class for any visual object, like labels, buttons etc. All views can have subviews, so you can add an image under a label etc. and do really wierd stuff if you want to. I am just saying this to free your mind about how you can use views.
Now, ViewControllers are supposed to hold to code to ONE view hierarchy. That view hierarchy is for that View Controller only.
When the user wants to navigate to another page, you have a few alternatives:
NavigationViewController - that should be used when the user wants to delve down into data, like opening a detailed view of an item in a list etc. The NavigationViewController gives you help with back buttons, proper animation etc. You "pop" a viewcontroller to go back one level. If the user click the back-button, this is automatic.
TabBarViewController - use that if you want a tab bar at the bottom of the screen. Each tab is connected to a ViewController, that has it's own view hierarchy.
PushModal - If you are in a ViewController and just needs to get some data from the user, which is not part of the normal navigation of the app, you can push a new ViewController modally. This is the way you interact with iOS built in ViewControllers. This is also a good way to get a value back from the view controller.
There you have it. Go learn more. :)
It sounds like, for what you are using, you should be using a navigation controller. This will automatically handle pushing views onto the stack and then popping them off again later. This will also automatically create a back button (it is customizable) in the navigation bar.
If you are using iOS 5 or 6, I highly recommend trying out "storyboards" in Interface Builder. Storyboards allow you to graphically represent transitions (called "segues") between different views.
On top of being easier to design and implement, another advantage is that, if in the future you want to change the design of your application, you don't have to trawl through all your code and manually update each view connection.
i'm currently developing an app for both Android and iOS, thing is... I started with Android and my app has several Activities with different layouts (Screens with different GUI's, if you are not familiar with android), most of them display very different contents; maps, lists with data from databases, images, text fields with buttons and so on (And most of the time the orientation of the screen changes).
The problem comes with iOS:
How do I create more windows from IBActions? (Is this a correct approach?).
Once I create a Window, how do I create a new Interface? (Do I need another .xib file?)
If once the user finishes with one Windows, does the previous window remains in memory and can be re-opened? (Can I use a navigation tab, even though the first windows was not a using it?) This is a major problem since iPhones do not have a back button and Android relies a lot on those...
Also, if I can't split my program in several windows, wouldn't my app use a lot of memory from destroying and building views?
I'm new to Cocoa development and I have already read a book about Objective C programming (which only teaches syntax and so on), another one about simple iPhone apps (all of them were done in one window, changing the views programmatically) and I'm currently reading another one, but i'm unable to find a simple answer to my problem...
I mean I get Obj-C and how to build iPhone apps (well kind-of) but maybe the problem is that I come from a more straight forward development in Android. Each time I see an iOS project, I see it like a total mess, and the documentation in developer.apple.com doesn't help much either, I'm unable to find what I want.
Hope someone has gone through this already and is willing to point me in the right direction, thank you!
I recommend that you start with the View Controller Programming Guide at the apple developer web site. I think you will find it very helpful.
To answer your questions, you can develop each of your views independently. You depending on your purposes, developing each from a nib file could work. In the app I'm working on now, I have some that I develop programmatically and some that I bring in from NIB files. It's all up to you. The guide I mention above discusses both approaches.
Regarding loading views from button presses, you can do that. Depending on the view controller you use, it can be very easily accomplished. WIth the navigation controller, for example, you just create an instance of the view and push it onto the stack. When you're done with the view, you pop it off and your back to your previous view.
With regards to memory, that is always a concern. You might want to take a look at The Memory Management Programming Guide.
Good luck. I'm just starting out with Android development myself.
Chris already provided a great answer but there are a couple of points I want to add to adress specific questions.
iOS apps normally only have a single UIWindow. Within that window you may present multiple views.
Apps are normally organized into several logical screens worth of content, each managed by some UIViewController subclass.
Each UIViewController instance has a root view which may contain many subviews. A UIViewController's view is expected to fill its window or some frame provided by one of Apple's container view controller classes (UINavigationController, UITabBarController, UISplitViewController, and so on). You should not add one UIViewController's view as a subview of another UIViewController's view.
UIViewControllers will attempt to unload their views when the application receives a memory warning if the view is not visible. See the class' life cycle methods like -viewDidUnload. You should support and take advantage of this behavior to reduce your memory footprint. Keeping UIViewControllers in memory without their views loaded should have a minimal overhead, allows you to keep some persistent state, and each controller's view can be reloaded when needed.
Normally to transition between views a control will send a message to the current view controller (often via an IBAction binding). The current controller will then trigger a transition to another view controller. It might do so by creating a new view controller and pushing it onto the current navigation controller or presenting the new controller as a modal. It might have a reference to some existing controller and present that. It might dismiss itself from a navigation stack to reveal the previous controller. It might even pass the message up the controller's hierarchy until some parent switches the visible tab, dismisses or presents a modal, and so on.
You might also trigger smaller transitions by responding to an IBAction by adding, removing, hiding, or moving subviews of a UIViewController's root view.
Flash Builder 4.5.1 Now enables you to build one application and Compile to multiple Devices
UPDATE: Try XAMARIN, it's part of Visual Studio:
https://www.xamarin.com/
XCode: "This template provides a starting point for an application that uses a single view. It provides a view controller to manage the view, and a nib file that contains the view."
What does that even mean? (ie what does Single view actually mean)
1) This means that your application will only have a single view screen that is active
2) This means that your application will be able to have as many screens as you like using a single view controller.
Ok now what if your application has multiple screens? not a single view screen, is still suitable under a view based application template?
Example
Screen1(main): on this screen you have 3 buttons, "Open Form1", "Open Form2", "Open Form3"
When the button is clicked it opens up the associated screen,
Press the "Open Form1" button opens up "Form1" screen2
Press the "Open Form2" button opens up "Form2" screen3
Press the "Open Form3" button opens up "Form3" screen4
When the user completes the form and submits it, a thank you screen is displayed
therefore in this example there would be a total of 5 screens.
Each form screen contains is different, textfield inputs, and information, is this considered as a view based application?
View-based app is just a template to say that your app will be view-based. That means that you can have any number of views you want, as this template comes with a view controller (that, as the name says, can be used to control the views... show/hide them with animation, for example).
The template starts with ONE VIEW that is added to the app view controller. You can add any number of views to that controller.
So, yes to your questions. You can use this to create the app you mention, where any of the "screens" you mention would be a view, for example and you can show each one using, for instance, the app view controller to animate each view showing or hiding.
That means the template will create one view and corresponding view controller along with app delegate, main window. That will also do the necessary things to add this view to main windows, and load when app runs. This is just a template. Then you can crate any number of views and view controllers as you want.
This means that the template you are starting the project with provides a single ViewController, and associated XIB for the View. As the first answer says you could use this template to build the application mentioned.
HOWEVER you may wish to think about how the user is going to interact with your app. Will you allow stepping back and forwards through the screens, in which case you may want to consider the Navigation Based app where you push/pop screens onto a stack to allow easy movement between then.
You might also have a concept of allowing the user to jump at will between each of the screen pages in which case you might want to implement a TabBar application.
Or you could just implement it all yourself. At the end of the day it will be your application design, and the template is only a starting point to get you going. I would suggest that if you are starting out with iOS development however to go with 1 ViewController matched a XIB for each screen you wish to implement to keep things simple.
I'm wondering if it is possible to start my app with all my tabs in the "up" state and show a "landing" view to the user. Kind of like a welcome/quick start. When they select one of the tabs, it switches views as normal.
Will you point me in the right direction?
Kind of like this:
If you're using a UITabBar/UITabBarController, I think you must have the selectedIndex set to some legal value. I don't think this is possible, nor can I find an app on my iPhone or iPod that mimics the behaviour you're looking for.
(The App Store app is as close as it gets, where it looks like it has an empty tab bar before it loads data from the Internet, but it could very well be that they are just re-using the Default.png and superimposing an activity indicator during loading.)
Note that if you tried to submit your app to Apple, they could easily reject it for using non-standard UI.
The way I would probably do this is to create a new ViewController that's just for this screen, but make sure it's last in the viewControllers array managed by the UITabBarController. That way, when you show the tab bar on the screen, you get the 4 tabs and the more button, but the currently selected view controller is not in the bar, meaning that all of the other tabs are unselected.
Once the user has satisfied the condition for showing the screen, you can discretely remove the view controller from the tab bar, and the user will never be the wiser.
I've been able to incorporate all of Apple's code, delegation, etc related to iAds, in simple view based applications.
Tab bar type applications seem more difficult, perhaps I don't understand the overall architecture of those apps. It seems that, say, if there are 3 tabs and views corresponding to those tabs that the other tabs sort of inherit or are attached to the first tab.
When working in interface builder, it seems that dragging an adbanner into the windows actually replaces everything that is there and building some kind of view container to put the "tab infrastructure and associated views" and an iad doesn't seem to fly.
I'm able to code by hand the pop of an ad in my code, which shows up when running the app under the first tab, but it doesn't show on the subsequent tabs, I was doing this in viewDidLoad. It seems the tab bar apps want to sort of own the entire screen realestate to some extent. Any thoughts? There's a UIWindow and the TabBarController, the window seems largely "blank" and otherwise purposeless.
What I would do is create a separate custom view, which you push onto your enclosed view in each tab just as part of the viewDidLoad process.