I've got a view hierarchy which is setup (programmatically) as follows:
Window.root = TabBarController-->UINavigationControllers-->UIViewControllers
I presume that's rather standard. Here's my problem:
I'm on Tab A. I want to navigate to Tab B, and call a method on the visibleViewController on Tab B.
// View Changes OK
[AppDelegate.tabBarController setSelectedIndex:tabB];
// nav = 0x387ABF i.e. Valid Address
UINavigationController *nav = (UINavigationController*)[AppDelegate.tabBarController selectedViewController];
// The problem:
nav.viewControllers; // this is nil
nav.topViewController; // as is this
nav.visibleViewContorller; // this too.
Even if I put the calls to nav.viewControllers in a separate method which is called from the Main Thread, I still get 0x0/nil.
What am I doing wrong?
A follow-up question is:
How can I pass information from one ViewController to another when changing tabs? (If I can't call methods on VC's from tabA to tabB)
I have a feeling it is related to my question here.
You should store the information in a common place, either a singleton or as you are a beginner just make a class and pass it down.
sharedDataObject = [[MySharedDataObject alloc] init];
firstViewController.myDataObject = sharedDataObject;
secondViewController.myDataObject = sharedDataObject;
Related
Rookie question: I am writing a program that will generate a specific string and then display it in a text window in a different view controller. I have been testing to ensure that the code in fact generates the string using NSLog commands and I know the code is working as intended. For some reason it is not transferring across the view controller and I cant figure out why. Any help? Here is a snippet of the code:
CreateStoryViewController.m
- (IBAction)makeStory:(id)sender
{
StoryLine *myStory =[[StoryLine alloc] init];
[myStory setStory];
self.story = myStory.plot;
NSLog(#"story is %#", self.story);//this is generating the correct story string
self.displayStoryController = [[BIDDisplayStoryViewController alloc] initWithNibName:#"DisplayStoryView" bundle:nil];
[self.view insertSubview:self.displayStoryController.view atIndex:1];
}
DisplayStoryViewController.m
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view.
BIDCreateStoryViewController *newStory = [[BIDCreateStoryViewController alloc] init];
NSLog(#"newStory.story is %#",newStory.story);//this generates null message
self.storyDisplay.text = newStory.story;
}
This is wrong. You're instantiating a new BIDCreateViewController object inside your second view controller. This is not the same as the original BIDCreateViewController object that pushed your second BIDDisplayStoryViewController.
You need to declare a string property in your BIDDisplayStoryViewController's header file.
Something like
#property (nonatomic, retain /*or strong, if using ARC*/) NSString *storyToDisplay;
Be sure to synthesize this in your implementation file as well.
When you create BIDDisplayStoryViewController inside your first view controller, you need to do it as follows:
self.displayStoryController = [[BIDDisplayStoryViewController alloc] initWithNibName:#"DisplayStoryView" bundle:nil];
self.displayStoryViewController.storyToDisplay = self.story;
Now inside your second view controller you can access this using self.myStory.
While this will solve your problem (and please do understand that it's not my intention to be rude here), I feel that there's a lack of understanding of how iOS (and OOP in general) works.
In your viewDidLoad method you are making a whole new story. This story is totally different from the one you made in the makeStory: method. You should add a StoryLine Property to DisplayStoryViewController.h, and set that after you init your displayStoryController.
make the intended variable a property type at .h file, so the other file can access it
I have a UITabBar with 5 tabs. I only wish to enable autorotation for a UIViewController that gets pushed onto the stack deep inside tab #3. So to be clear: tap UITabBar item 3, and you get tabbar item #3's root UIView, which should not autorotate. Tap and get another UIViewController pushed onto the stack (via a UINavigationController). Tap again, and get another UIViewController pushed onto the stack. Only here should this UIView autorotate.
The other 4 tabs should not rotate at all--not the root view of the tabs, nor any of the child views of the tabs.
Can someone tell me what approach I should use? I read that every single tab needs to respond "YES" to willAutorotateToInterfaceOrientation.
In each view's shouldAutorotate..., you could call a method in the root view controller that checks what is currently being displayed. If the deep-level view for tab 3 is on display, it will return YES, otherwise NO, and the views will, in turn, return the same.
Edit -- more detail per user798719's request:
Your root view controller knows which view is on display. You add a method to the root view controller - (BOOL) isDeepLevelTab3Displayed;. The method checks whether the deep-level view for tab 3 is on display and, if so, returns YES, otherwise returns NO.
Each sub view controller’s shouldAutorotate… method will get a ref to the root controller so that it can call isDeepLevelTab3Displayed.
If you’re using a navigation-style controller, you can get the ref like this (self is the sub controller):
NSArray *arrayOfControllers = [self viewControllers];
UIViewController *rootController = [arrayOfControllers objectAtIndex:0]; // per UIViewController class ref, root controller is at index 0
Or you could get anything in your project like this:
YourProjectAppDelegate *appDelegate = [[UIApplication sharedApplication] delegate];
UIViewController *rootController = appDelegate.rootController; // or appDelegate.intermediateClass1.intermClass2.rootController — however you set up your project
So every sub controller would do this:
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation {
UIViewController *rootController = [[self viewControllers] objectAtIndex:0];
return [rootController isDeepLevelTab3Displayed];
}
Therefore, every subcontroller would return YES when autorotation should happen, fulfilling the requirement you mention at the end of your question.
However, if all your subcontrollers are instances of UINavigationController, you could determine which view is currently on display directly, by calling visibleViewController. Then you just need a way of checking its identity.
You could check the controller’s nibName or title, for example, against a constant, or add an integer property intControllerIdentity to all your controllers and set them in the controller’s initWithNibName…
The integer-property scheme might be best, because it won’t be affected should you later change the nibName or title.
You’d add constants to some class whose h file is imported by all the controllers (or, if all the controllers are instances of the same class, put these constants in that class’s h file):
#define kFooController 1
#define kBarController 2
#define kRotatableController 3
And you’d set it like this:
self.intControllerIdentity = kRotatableController;
And check it like this:
if (self.intControllerIdentity == kRotatableController)
Hope that helps. But evaluate this added detail with a critical eye; I have worked with autorotation but not yet with navigation controllers.
I am working on an iPhone app. Initially, I had my pickerview in the same screen so this was just a one page app. After skinning it i realized that i want the pickerview on it's own separate page. So i did that. However, my pickerview originally would update uilabels and other objects on that same page. How can I have my pickerview access those objects from it's new view?
- (IBAction)ShowPickerAction:(id)sender {
if (self.theView == nil) {
theView = [containerView initWithNibName:#"containerView" bundle:nil];
theView.parentView = self;
}
self.theView.modalTransitionStyle = UIModalTransitionStyleCrossDissolve;
[self presentModalViewController:self.theView animated:YES];
}
That is the method I am using to call my new view. But line 3 of the above code gives me the error "No known class name for selector initWithNibName:bundle". I think that error is related to something that i did wrong in my header file. My new class is called containerView. So i did this in my header:
#interface ViewController : UIViewController {
containerView *theView;
But that gives me the error "Unknown type name containerView" even though i do have a class named containerView!!
Look into uiappdelegate protocol or try passing values to through a static function to the previous page.
Use a delegate to pass information back and forth to the view object that instantiatrd the picker view. You want to keep your code coupling as loose as possible, especially if you might like to drop it into your next project. Using a delegate and/or blocks are some of the best ways.
I am using navigationcontroller. i have (Root,A,B,C,D) class. i want to sand a string test value Class D to Class A via popToViewController.
Please give me suggestion.
Thanks
UINavigationController maintain the list of all pushed controller in viewControllers and the root controller always reside at 0.
MyAController *myController = (MyAController *)[self.navigationController.viewControllers objectAtIndex:0];
myController.myText = #"My String" ;
[self.navigationController popToViewController:myController animated:YES];
You might want to rethink your design, but since you haven't given enough information for me to suggest how, you could just try this:
A *aController = (A *)[myNavController rootViewController];
[aController setMyString:#"your string here"];
[myNavController popToRootViewControllerAnimated:YES];
Make that string as property of class a then you need to access that object of the view A from navigation stack in class D.
And then access that property for using.
If Class A is rootView then jtbandes answers helps you otherwise pick it up from stack code some thing like this
if([self.navigationController.viewControllers count]>3)
A *aController=(A *)[self.navigationController.viewControllers objectAtIndex: [self.navigationController.viewControllers count]-4];
if your navigation is A->B->c->D
then you can access c by [self.navigationController.viewControllers count]-2 similarly B by -3 A by -4.
There are several approaches to achieve this.
Using Notifications.
Using Delegates.
Using Outlets/Properties.
You could also create a ControllerA instance var in your ControllerB and then pass the ControllerA (self) to ControllerB(ex: by a method) before call pushViewController from A to B. You can do the same from B to C...etc; i think the best solution is that of Jhaliya in case you want to work with navigationControllers.
I'm trying to make a modal view which displays the champion of my app.
there's a NSMutableString variable called champ in modal view,
which is supposed to be updated by returnChamp function in main view.
the champ string is correctly set in main view,
but in modal view, the champ value appears as (null).
In fact, it seems it doesn't even go into the returnChamp function.
so apparently something wrong with my calling or implementing returnChamp,
but I have another function that does the similar, and that works fine.
could anyone please help me?
-(void) mainView{
.....
champ = [[currentPlayers objectAtIndex:playerIndex] retain];
NSLog(#"%#",champ);
modalWinner = [[winner alloc] init];
modalWinner.modalTransitionStyle = UIModalTransitionStyleCoverVertical;
[self presentModalViewController:modalWinner animated:YES];
}
- (NSMutableString *) returnChamp{
NSLog(#"returnChamp");
return champ;
}
//in modalWinner
-(void) modalView{
..............
champName = [[NSMutableString alloc] init];
NSLog(#"%#", [(MainViewController *)self.parentViewController returnChamp]);
champName = [(MainViewController *)self.parentViewController returnChamp];
UIImage *champImage = [UIImage imageNamed:champName];
}
self.parentViewController is probably not actually a reference to your object. For some reason, it seems that the framework always insists on setting a UINavigationController as self.parentViewController - even for modals, and to the extent that it will create one if there isn't already one. This is probably going unnoticed because you're casting it to your MainViewController type.
You'll need to find a different way of making your original object available to be communicated with, or perhaps pass the appropriate value to the newly-instantiated controller before you present it.
For example, if you add a champName property to the modal class, you can do:
modalWinner = [[ModalWinnerViewController alloc] init];
modalWinner.champName = myValue; /* Set value before presenting controller */
[self presentModalViewController:modalWinner animated:YES];
There will probably be some code needed to update the UI with this value. The viewWillAppear method of the modal view controller is a good place for this as it is called by the framework immediately before the view is presented.
Note that this property-based approach could be used to keep a reference to your intended parent object, as well. And see here for a different approach to solving a similar problem.