I'm building an app that uses a TabBar controller in which one of the view controllers an NSMurableArray is set (and potentially modified). I then need to use that same array to populate a table on one of the other views when it is selected. I've looked into using a singleton (as was provided as an answer to this question on this website already) but haven't had much luck.
Would a singleton be the best way to go or is there a better way of doing it? I'd appreciate any help/examples if possible?
You have several options for doing this, here are 2...
1.) have the NSMutableArray be a property of the one view controller so the other one can access it like viewController1.mutableArray. To do just add #property (nonatomic, retain) NSMutableArray *mutableArray to your viewController class (using whatever name you want).
2.) Pass the array through a method from the first viewController to the other and keep a reference to that array in the other class.
You can 'attach' controllers to each other, just like you 'attach' ui elements to controllers. E.g., declare variable
IBOutlet ReferencedController *referencedMenu;
and then in Interface Builder draw a line between referenced and referencing controllers.
Do I understand you correctly?
Thanks for your help, in the end this is how I have done it:
UIViewController *tmpNamesListVC = [self.tabBarController.viewControllers objectAtIndex:1];
self.names = [tmpNamesListVC names];
When it builds i'm getting a 'UIViewController may not respond to -names' warning but everything compiles and runs as it should.
Related
I want to do something like UITabBarController. UITabBarController has property viewControllers into which I can add instances of UIViewController * in IB. I'm trying to do the same think with my own VC:
#property (nonatomic, copy) IBOutletCollection(UIViewController) NSArray *viewControllers;
but this doesn't work. Is it even possible for us?
EDIT 1.
Ramshad posted the proper sample, but using XIB. I would like to achieve it using storyboards.
EDIT 2. - at the end of bounty worth...
I question vaderkvarn's post because in case of UITabBarController it works. Also as Ramshad posted, it is possible in NIBs. So far, dasblinkenlight's post is the most correct, but not answers the question. I'm holding this question opened because we shall find out if it's restricted for us or what is the way.
PS: Why these downvotes?
Although it does not look like you can connect UIViewControllers to IBOutletCollections (or there are too many restrictions placed on using them), there is a simple solution that works when you use storyboards. This code goes into your viewDidLoad method:
_viewControllers = [NSArray arrayWithObjects:
, [self.storyboard instantiateViewControllerWithIdentifier:#"Controller1"]
, [self.storyboard instantiateViewControllerWithIdentifier:#"Controller2"]
, [self.storyboard instantiateViewControllerWithIdentifier:#"Controller3"]
, nil];
The reason why the outlet collection solution does not work is that a View Controller is not an outlet. From the documentation:
An outlet is a property that is annotated with the symbol IBOutlet and
whose value you can set graphically in a nib file or a storyboard.
A view controller is not a graphical object.
If you want to use an IBOutletCollection, you should only use one view controller, and put the views in the collection.
But if you want one controller for every view, you need to go for a more programmatic approach. An array with view controllers might be a good start, but I couldn't say as I don't know what you want to do with them.
Edit:
To be more clear as you don't seem to catch my point:
No, it does not has to be a way. A Storyboard is not an API, it is a graphical tool for drawing scenes and segues. It is specially designed for things like Tab Bar based apps.
If you right click on your Storyboard file and choose open as -> Source Code, you will see that a Tab Bar Controller have special elements that other View Controllers do not have. To mess around with the XML in a Storyboard file is beyond me.
If you want to go with Nib files, use Ramshads answer.
If you want to get as close as possible with storyboards, go with dasblinkenlights answer.
But the answer to your question (as far as I know) is NO, there is no way to accomplish this with storyboards. If it were, it would have been documented, which it is not.
I have done your requirement using UISegmentedControl + IBOutletCollection + presentViewController.
You can use any control instead of UISegmentedControl as your wish.
I have Added 3 different UIViewControllers to Xib and labelled as ViewController1,2,3.
I also added 2 extra methods. One for presenting the corresponding view and another one for dismissing the earlier populated view.
I have attached the Xib settings screen-shot below.
You can use only one UIViewController instead of 3 and reuse it with some logic :)
The methods are below:
#property (strong, nonatomic) IBOutletCollection(UIViewController) NSArray *ViewCollection;
//dismissing the earlier populated view
- (IBAction)dismiss:(id)sender {
[self dismissViewControllerAnimated:YES completion:nil];
}
//presenting the corresponding view.
- (IBAction)resetAction:(id)sender {
UISegmentedControl *mySegment = (UISegmentedControl *)sender;
int index = 0;
for (UIViewController *viewItem in _ViewCollection) {
if (index == mySegment.selectedSegmentIndex) {
[self presentViewController:viewItem animated:YES completion:nil];
}
index++;
}
}
You can download the my sample application from here
Xib Settings Screen-shot
here i want to ask a question regarding view controller template for iphone or ipad.
question: i want to design a view controller with some images and make it as common template and need to use it as a template to other view controller too. (also some buttons and labels are the inclusions if needed)
(ie) when ever i call that class, automatically its components should be inherited to calling class.
is it possible?
it would be grateful if anyone answers me the suitable or favourable
I don't know how adMob works but like everything else you can create a BaseViewController in which you can add your adMob(in the viewDidLoad method) and then all the other viewControllers can subClass this BaseViewController. just call [super viewDidLoad]; in the viewDidLoad methods of your viewControllers and you will have it...
hoping this sorts your problem... :) this is what I usually do.
Sounds like you just need to derive your view controllers from a common base class. Is there something that you want to do that's not provided by inheritance?
Yes it is possible.
You need to create #property for your components to re use them in other class
in class1:
#property(nonatomic,retain) NSMutableArray *exercisesArray;
in class2:
#property(nonatomic,retain) NSMutableArray *array;
nextViewController *start = [[nextViewController alloc]initWithNibName:#"nextViewController" bundle:nil];
next.array = exercisesArray
I have two view controllers, one is MainViewController, the other is SetupViewController. I want a UILabel on MainViewController to set the text to the contents of a UITextField from the SetupViewController when a button is pressed in the SetupViewController.
In SetupViewController, I have this in the IBAction:
- (IBAction)donePressed:(id)sender {
MainViewController *mvc = [[MainViewController alloc] init];
[mvc.testLabelOnMVC setText:testTextFieldOnSVC.text];
[release mvc];
}
testLabelOnMVC (and testTextFieldOnSCV, with respective terms) is
#property (nonatomic, retain) UILabel *testLabelOnMVC;
and is also synthesized.
Every time I try, it doesn't work. Nothing happens, nothing changes. I have no errors or warnings. Can anyone help me out?
The view of your MainViewController does not exist until you reference the MainViewController's view property (which forces viewDidLoad to execute). You must reference the view (or otherwise force the view to be constructed) before you attempt to modify any UI objects in the MainViewController.
You are allocating a new MainViewController when you press the button, then you are setting the text of the label on this new controller, not on the MainViewController that your app is showing.
To fix this, create either and IBOutlet or iVar that points to the original MainViewController and set the text on that instead.
Easiest way is to create a #property in the main view controller and write the text in there. Then just read it in the second MVC's viewDidLoad.
The only views that MainViewController should worry about are the ones that it owns; it shouldn't be trying to access the view hierarchy managed by SetupViewController. Likewise, SetupViewController should not directly modify views in MainViewController's view graph.
The right way to do what you're asking is for the two controllers to talk to each other, either directly or via the data model. For example, let's say that your MainViewController instantiates SetupViewController. If that's the case, it'd be natural for mvc to set itself as svc's delegate, so that svc sends it a messages like -setupController:didUpdateTestStringTo:. MainViewController's implementation of that method could then save the new test string somewhere and update it's testLabel field.
Another example: MainViewController instantiates SetupViewController. SetupViewController contains a field where the user can enter a new value for the test string. Before exiting, SetupViewController writes the contents of that field into NSUserDefaults or some other common data storage. When control returns to MainViewController, that object reads the shared data and updates itself as necessary, including setting the new value for testLabel.
There are other variations on the same theme, but the common thread here is that neither view controller has to directly access views that it doesn't own.
You can change the text of the label if the view is already loaded. Instead of initializing the viewcontroller, retrieve it from the view stack if you are using navigation controller.
I dont know if your viewController is already loaded or not.
I'm new to OOP and I'm confused about this following line on chapter 6 of head first iphone development:
addDrinkVC.drinkArray = self.drinks
the purpose is to assign the self.drinks NSMutableArray to another NSMutableArray in modal viewController addDrinkVC.
But why when you added an object into drinkArray in modal view and returned to the rootView and reload the tableView, self.drinks also gets changed? Is it related to the concept of pointer?
Thanks!
Unless drinkArray is declared with #property (copy), the contents of the array are not copied. This does indeed have to do with pointers. Since the array is mutable, and since you are not copying it – only adding a new reference to it – any changes made to either reference will be visible on the other. In other words, there is only one actual array in use.
I have been having huge issues with this, so I drew a diagram...
alt text http://tomsfil.es/7bdead0a.png
I successfully get to the CLASS A - METHOD B but at that point, IBOutlet Z is Nil? :(
Any ideas?
note
Somebody told me it might be an Overrelease and to use NSZombieEnabled but that confused me
It's all a matter of when you call the class. Right after you create a view controller with initWithNibName, nothing is actually wired up yet - it's only after the view is created that IBOutlets are created and wired in.
One trick is that you can simply ask the view controller for .view, like so:
myViewController.view;
Then the view will be created and the IBOutlet will exist. A better method though, is to create properties on the view controller that you set, and then either in viewDidLoad, or in viewWillAppear you use those properties to set values for your outlets.