I have a very simple iPhone view based application I need help on. It's a view based application with a nav. bar in the footer that switches between 4 view controllers.
What I need to do is pass a UILabel value from view 2 to view 4. The UILabel field is a value calculated in view 2, but I want it to appear in view 4 (if 5+5=10, I want the 10 to appear in view controller 4, not view controller 2).
How do I go about doing this? Does anyone have any sample code I can review? I've searched awhile in Apple's docs and online and haven't found anything helpful yet. Keep in mind I'm a real newb. when it comes to development. I'm just starting to learn!
Thanks in advance.
There are a few ways. I would probably just have a variable created in the application delegate's interface and just change it and access it there.
NSObject *myVariableFromDelegate = [[[UIApplication sharedApplication] delegate] myVariable];
[[[UIApplication sharedApplication] delegate] setMyVariable:10];
Take a look at NSNotificationCenter. You can send a messages and handle them anywhere in the app, best solution in most similar cases.
The application delegate might work for you, but if you are going to have a lot of values to keep track of, you are probably better off implementing a separate class for your data. Otherwise it will get unwieldy quick.
When you load a new view, you pass off a pointer to the data cass to that view controller so that the current values can be pulled out and put into the correct fields. In addition, you could use register for notifications in the view controller to catch any changes that other views make. Just make sure you de-register the notification when the view unloads, and you should be good.
Related
This is my first app using storyboards/segues, and I'm pretty sure the answer to this is easy, but I'll be as thorough as possible in describing my issue.
I am making a simple app which has a Tab Bar Controller scene and two View Controllers.
My app launches by being sent a URL from another app. The application:openURL:sourceApplication:annotation: method in the app delegate performs some work to determine
which tab to display first, and
what information to display on it.
My goal is to use the performSegueWithIdentifier method (I'm open to alternatives though) from within the AppDelegate to select the tab, and also find a way to send a method to the instance of the view controller created by the storyboard.
Issue #1 is that I can't set an identifier. When I select the tab "relationship" there are no choices available in the Attributes Inspector (it says "Not Applicable"). How do I set a name for this segue? Can I? Or is there some rule under which UITabBarController segues can't be trigger programmatically?
Issue #2 is that I can't find a way to have a pointer to the view controller. Pre-Storyboard I would alloc and init a new view controller and then set it up, but here if I do that, it does not get displayed when my app launches (I think this is because Storyboard is displaying a different instance of the same view controller.)
I know this post is long, but I feel like I'm missing something simple. What is it?
Sounds like you need to have your AppDelegate set the entry point to your storybard.
I am a newbie in all this as will be apparent really soon.
I am using the iOS: Application: Tabbed application template. I have placed a UIImageView in the first view and two standard rounded buttons. One button is attached to an action in the FirstView Controller which places a picture into the UIImageView. The second button is attached to an action in the AppDelegate which calls a method in the FirstViewController which in turn places a second picture into the UIImageView.
The AppDelegate method does not replace the picture. It doesn't crash… it just does not seem to do anything.
How can I manipulate the view in the First and Second View Controller from the AppDelegate?
#dasdom
Well that's one issue explained. I've been reading the theory of MVC and trying to put it into practice now. Short version is I am trying to write a Battleship app for practice. Was planning on using the first screen to setup the game pieces, prefs, etc.. and use the second screen for actual game play.
I've created another class to use as my "brain center" but I ran into the same issue of not being able to manipulate anything on the screen for the first or second views. (That's why I tried the appDelegate).
That's my life story right now… can you throw some pointers my way on how to proceed and how to solve my one of many problems?
First you shouldn't do that. The AppDelegate should only be responsible for bringing the first view onto the screen.
Second you should have a look into the Model-View-Controller design pattern. Search for it in your preferred search machine.
But I you really still want to do that you should have a look into delegation and/or notifications. For example you could send the First View Controller a notification from the AppDelegate to change the image.
I have looked at the sample generated by xcode when creating a new UISplitView app on the iPad along with countless other tutorials and the documentation from the apple developer site. I have not seen an example where the UISplitView used was not the root of the application. Is this even possible?
What I am trying to accomplish: I have a UITableView to start out and once an item in the list is selected I would like to display a splitview with two different sets of information that is based on the item that was selected.
I curious if this type of implementation is even possible, or just frowned upon, and why. If it is possible, how would I go about implementing and hooking up a UISplitView to behave in this way?
Edit: I'm updating this with what I have. I can now switch to my UISplitView, though the transition is not animated. What is the way to correctly switch to a UISplitView so the transition is animated?
Code for switching right now:
[appDelegate.window addSubview:appDelegate.splitViewController.view];
appDelegate.window.rootViewController = appDelegate.splitViewController;
EDIT 2: In hopes of bumping this back up so more people see it, I have managed to switch from my navigationController to my splitViewController, but when I add the button to be able to navigate back, nothing I do makes a difference and I seem to be locked in. I tried reverse mirroring the code to switch to the splitViewController, but that had no affect, and I am completely out of ideas. Can anyone shed some light on this?
You should always use SplitViewController as a rootViewController: Split view controller must be root view controller
There may be some hacks around it, but when Apple have a strong recommendation and design guidance, I suggest to try to re-think your design before going against the platform -it should save you effort in the long term.
I recommend using the MGSplitViewController, it also works as a non-rootViewController, even nested into an another MGSplitViewController, and there's i.e. a one-liner for the animation to blend in the Master-View, if that is what you want.
In your UITableView didSelectRowAtIndexPath method you would have something like:
UISplitViewController *mySplitView = [[UISplitViewController alloc] init];
[self.navigationController pushViewController:mySplitView animated:YES];
[mySplitView release];
Probably you'll want to subclass UISplitViewController just like you would other view controllers and set in there the master and detail views and so on.
I'm trying to put an iAd banner in an app that is based on a UINavigationController (it's not the standard nav-base app proposed by xcode, cause I don't need the table view).
I'd like to place an ADBanner on its bottom, to be always visible, no matter how the user pops and pushes views.
I studied the iAdSuite example in the apple sample code, but, though it's reported among the "best practices", I don't think it's the best practice for what I need. It basically declares an ADBannerView in the app delegate class and then implements the ADBannerViewDelegate methods for every single view the app needs. That means implementing the ADBannerViewDelegate methods over and over again on every view controller class you need! It doesn't seem too smart... :(
I'd rather prefer to have an approach more similar to what Apple itself does in the tab bar based app, where you have a part of the window always occupied by the tab controller and all the views switching above without affecting the tab bar view below.
You can't directly put an ADBannerView along with the nav controller in the app delegate, because ADBanner needs to be placed in a view controller (you get a runtime error otherwise).
I tried to subclass from UIViewController, implementing the ADBannerViewDelegate in this class, and place it in the rootViewController along with a UINavigationController but I'm not having good luck with this approach...
Has anybody found a good, simple way to to this? Any hint?
Thank you for any help...
You can have just one class for ADBannerViewDelegate, and just one instance of ADBanner itself. When the currently active view changes, remove ADBanner from the old view, add it as a subview to the new view.
EDIT:
to clarify, you don't need each view implement the ADBannerViewDelegate. You only should have one class implement it (that class doesn't have to be a view controller for that matter).
You would also need to maintain a somewhere a property that would point to the currently active view (e.g. you can update that property in your Navigation Controller's navigationController:didShowViewController:animated:, or come up with your own protocol for that if your views appear in a more complex way).
Then in your ADBannerViewDelegate you'd just resize the view currently pointed to by that current view property. The actual view doesn't even have to know it has an ad in it ;)
I'm creating an iPad app based on a UINavigationController (with the bar hidden) so I can push and pop other viewControllers for navigation around the app. However, I am now wanting to add a section in which there are two viewControllers that I want to be able to switch between, so in other words they are side-by-side, rather than hierarchical.
Is it okay to use a UITabBarController for this? I am aware that on the iPhone it is recommended they are used only at the root level of the app, but since this is an iPad app I wondered if I could use it? Also, I guess I need to create an empty viewController, create a UITabBarController within it and set the delegate to it, then add the two viewControllers to it... So in effect I will have a viewController within another viewController, and when I have done that in the past the results have been very flaky.
Can I do it this way? The only other way I can think of doing it is to have two plan UIViews within a UIViewController, but that also means I shouldn't really put any business logic in them (bad MVC!), and not being able to will be a right pain in the a**.
Any ideas?
Thanks!
:-Joe
EDIT: I also need to be able to swipe-animate between the two VCs within the TabBarController, AND have a menubar over the top which doesn't animate... Can I do this?
Sure.
I do this kind of thing all over the place in an app I'm working on. I actually have several different types of "toolbars" that can be optionally shown at different times.
What I do is create a "parent" member in my toolbar's class - and when a button is pressed, I have the toolbar call a method in the parent class to do whatever needs to be done - (i.e. display another view).
This avoids the whole mess of creating a view inside another view (or viewcontroller inside another viewcontroller - or whatever) - the toolbar can take the button hits, but all the views are opened by the root view/controller.
Hope this helps/makes sense!