I have got a single view in my storyboard, which I add to my current view by doing the following :
MainViewController *mvc = [self.storyboard instantiateViewControllerWithIdentifier:#"MainController"];
[self.view addSubview:mvc.view];
The view appears, but everything I do after it appears, leads to a crash. What am I doing wrong ?
Here is an example when it crashes:
-(IBAction)showUsername:(id)sender{
[testLabel setText:#"username"];
}
Everything is hooked up in storyboard as well, so falsely linked connections should not cause the problem.
You instantiate a new view controller:
MainViewController *mvc = [self.storyboard instantiateViewControllerWithIdentifier:#"MainController"];
But you do not retain it. Your view hierarchy is, as soon you added it to another view.
[self.view addSubview:mvc.view];
So when a button is clicked, a message is sent to you IBAction, but your view controller has been released already. To prevent this from happening, retain your mvc variable, for example somewhere in a property.
#property(nonatomic, strong) MainViewController *controller;
self.controller = mvc;
I can think all reason before you show log...
Turn NSZombie on in the Product>>Edit Scheme you should get more descriptive Error showing then. Then you can add it.
Make sure your method is declared and implemented correctly. Also make sure you have IBOutlet UILabel * testLabel in your .h. The only other problem I can think of other than that is how you hooked it up. Does it only crash when you press the button?
This line is wrong this will be why you are getting the error.
MainViewController *mvc = [self.storyboard instantiateViewControllerWithIdentifier:#"MainController"];
[self.view addSubview:mvc.view];
replace it with this
MainViewController *mvc = [self.storyboard instantiateViewControllerWithIdentifier:#"MainController"];
[self presentModalViewController:mvc animated:YES];
In storyboards you are not adding a subview you are doing one of three things presenting a modal, pushing it on to the navigation controller stack or making a custom one of these.
Related
I am trying to convert my App to a Storyboard, but am having some problems.
In de previous model I could have an 'actionClass' in my AppDelegate which I called when I needed to pop-up a view.
E.g.
DOArticleViewController *articleView = [[DOArticleViewController alloc] initWithArticle:article notification: notification nibName:#"DOArticleViewController" bundle:nil];
[[self navigationController] pushViewController:articleView animated:YES];
But now with the storyboard it does not work anymore.
Then I tried the following code in the AppDelegate:
id currentController = [[[[self window] rootViewController] navigationController] visibleViewController];
[currentController performSegueWithIdentifier:#"settingsSeque" sender:nil];
Don;t think this is the best anyway, as only the rootViewController has all the seques needed, and might not be the visibleViewController, but one step at a time.
With this the only thing I see happening is the message and no action:
Unbalanced calls to begin/end appearance transitions for UINavigationController: 0xb428e00.
I spend a view hours now on trying to figure out to get this to work, but am realising that it might be better to go back to the traditional independent XIB files....
I solved with the answer given in this question: ios: Accessing a navigation controller from app delegate
I tried to get the Navigation Controller, but this was nil and I didn't realise it.
My navigation controller was the rootViewController, so that is also the NavigationController.
Casting the rootViewController to NavigationController and invoking 'visibleViewController' worked fine after that!
I have a splitViewController that has a master and detail view controllers. The code below is from the master and it creates the new view in the detail:
UIViewController *controller = [self.storyboard instantiateViewControllerWithIdentifier:[NSString stringWithFormat:#"%#",[self.defaultSettingsMenuItems objectAtIndex:indexPath.row]]];
[self.detailViewController.view addSubview:controller.view];
detailViewController is a global instance of DetailViewController. In the detailViewController, I have many textFields and need to utilize the UITExtFieldDelegate. However, I think that the detailViewController isn't self at that point, and that's why I'm getting EXC_BAD_ACCESS errors on using the TextFieldDelegate methods in detailViewController.
EDIT: I have now found that the subView delegate methods only work for the viewController I setup as the rootViewCOntroller relationship from within Storyboard. Ex. If I have 6 views in the default menu settings above, whichever one I have setup as the first and root view in storyboard will work correctly. Any and all other subviews shown (from making a new selection in the master view) will not work properly. I think this will help diagnose the problem.
I am not familiar with storyboards, but I don't see you setting the detailViewController's delegate anywhere. You probably need to have something like self.detailViewController.delegate = self; somewhere before you yield control over to the subview.
This all I needed, the second line:
UIViewController *viewController= [self.detailViewController.storyboard instantiateViewControllerWithIdentifier:[NSString stringWithFormat:#"%#",[self.defaultSettingsMenuItems objectAtIndex:indexPath.row]]];
if (self.detailViewController.childViewControllers.count >= 1) {
NSLog(#"childViewControllers: %#",self.detailViewController.childViewControllers);
[[self.detailViewController.childViewControllers objectAtIndex:0] removeFromParentViewController];
}
[self.detailViewController addChildViewController:viewController];
[self.detailViewController.view addSubview:viewController.view];
EDIT: I've updated my answer with the if look to remove viewControllers from the stack. Slightly hacky, but functional.
I copied a working viewcontroller class from another project into a new project. I can't get the view to load in the new project. In the old project I used presentModalViewController. In the new I cannot get the view to load using either presentModalViewController or presentViewController
I am trying to load the present the view from my main view controller.
Here is what my main view controller interface looks like...
// ViewController.h
#import <UIKit/UIKit.h>
#import "RequestDialogViewController.h"
#interface ViewController : UIViewController <RequestDialogViewControllerDelegate> {
}
- (void)requestDialogViewDidDismiss:(RequestDialogViewController *)controller withResponse:(NSString*)response;
I am using presentModalViewController like this...
RequestDialogViewController *requestIPViewController = [[RequestDialogViewController alloc] initWithNibName:#"RequestDialogViewController" bundle:nil];
navigationController = [[UINavigationController alloc] initWithRootViewController:requestIPViewController];
[self presentModalViewController:navigationController animated:YES];
and presentViewController like this...
RequestDialogViewController *requestIPViewController = [[RequestDialogViewController alloc] initWithNibName:#"RequestDialogViewController" bundle:nil];
[self presentViewController:requestIPViewController animated:YES completion:nil];
What am I missing in the new project? The init method fires, but viewDidLoad does not and nothing is displayed.
Thanks
If ViewController is the root view controller, it can't present a modal view controller from within its own viewDidLoad, because at that point it doesn't have information like the screen size.
If other view controllers have already displayed, this will work. If the root view controller is a UINavigationController, you will see a view sliding in from the right while the modal view slides up from the bottom.
Anyway, for your ViewController, the soonest you could present it is after it has become visible. Using a timer for this is unreliable; older and slower devices have dramatically longer load times.
For more reliability, implement viewDidAppear: for ViewController. Do still use your timer system to add an additional delay; a fraction of a second should be sufficient. Although presenting the modal view controller from within viewDidAppear worked for me in the iOS 5.1 simulator, Presenting a modal view controller when loading another ViewController says it sometimes doesn't happen.
I have it resolved. I was trying to present the view from view did load of the main view controller. Not sure why it does not work there, but instead I am now setting a timer which calls a method to present the view controller after the main view loads and it works fine now using...
[self presentViewController:requestIPViewController animated:YES completion:nil];
Thanks to those who replied.
As #Dondragmer said, if you want to present your viewController in root view's viewDidLoad, it will fail.Once your viewController is ready for that, you can present your new viewController.
So, you can do that in
- (void)viewDidLayoutSubviews {
//present here
}
I encountered the same problem. But my situation is the presentViewController is called after the dismissViewControllerAnimated for another ViewController. My solution is to move the presentViewController to completion block of dismissViewControllerAnimated.
Present a modalViewController:
For the benefit of all starting programmers, type it instead of copy paste.
myVC *viewController = [[myVC alloc]initWithNibName:#"myVC" bundle:nil];
viewController.modalTransitionStyle = UIModalTransitionStyleFlipHorizontal;
[self presentModalViewController:viewController animated:YES];
[viewController release];
It looks like you were trying to present a nav controller as a view controller in the first sample, then you were using the wrong method in the second one.
I am pretty new to iPhone programming, and was playing around with an app yesterday trying different scenarios with view controllers and nib files. So, I started a new app with a FirstViewController (FVC for short) and an FVC.xib.
I layed out a quick view in FVC.xib and ran the app - view displays, great.
I now wanted to have a second view I could add on top of the main view. So I went ahead and created SecondViewController.xib (SVC) but did not create the .m and .h files. I went about trying to load both these views from the same view controller, and here is where my question lies:
I created a button in FVC.xib and created an IBAction like this:
- (IBAction)loadSVC {
FirstViewController *viewController = [[FirstViewController alloc] initWithNibName:#"SecondViewController" bundle:[NSBundle mainBundle]];
secondView = viewcontroller.view;
[viewController release];
[self.view addSubView:secondView];
}
So this works great and adds the contents of SVC.xib, but when I try and remove that view from the superview, the app crashes:
[secondView removeFromSuperview];
If I actually create a view controller for SVC, use that to instantiate my view in FVC, and move the remove code to the SVC:
[self.view removeFromSuperview];
Everything works. My question - I kind of get why my first method crashes, but I was hoping someone could explain why and what goes on behind the scenes. I'm still a noob with object oriented programming, so what is actually happening in my first case where I create a new instance of FirstViewController and add its view to self.view? Why can't I release it (I assume because the original view is associated with FirstViewController, and when I create a new instance with the second xib it messes everything up) - I'd love a more technical explanation as to what is happening...
Thanks much!!
EDIT to add more info in response to Nick's reply below
Nick - so your answer did clear my thinking a bit in regards to the retain count, etc... I did another test app trying to get this working from a single view controller - think, for example, that I wanted to display an Alert or Welcome message to the user (I know in a real app there are different methods to accomplish this, but this is more of a learning experience) -- so I have my main view # MainViewController and layout my alert message in a xib called alert.xib -- so there is no logic behind the alert message, no reason for it to have a view controller that I can see, my end goal being loading/unloading this on top of my main view from the main view's view controller (or understanding why it is impossible)
I tried this using instance variables as you recommended:
In MainViewController.h:
#import <UIKit/UIKit.h>
UIViewController *secondController;
UIView *secondView;
#interface MainViewController : UIViewController {
}
#property(nonatomic, retain) UIViewController *secondController;
#property(nonatomic, retain) UIView *secondView;
- (IBAction)loadSecond;
- (IBAction)removeSecond;
#end
In MainViewController.m:
#import "MainViewController.h"
#implementation MainViewController
#synthesize secondController, secondView;
- (IBAction)loadSecond {
secondController = [[MainViewController alloc] initWithNibName:#"alert" bundle:[NSBundle mainBundle]];
secondView = secondController.view;
[self.view addSubview:secondView];
}
- (IBAction)removeSecond {
//I've tried a number of things here, like [secondView removeFromSuperview];, [self.secondView removeFromSuperview];, [secondController.view removeFromSuperview];
}
- (void)dealloc {
[secondController release];
[secondView release];
[super dealloc];
}
So - this works to load the alert view, but the removeSecond button does nothing (I did use NSLog to verify the removeSecond method is fired) - why?
Second, and most importantly - is this even possible, or is it horrible practice? Should every nib/view I am manipulating have their own view controller? Am I wrong to think I could just make a new instance of MainViewController and use it to display and remove this no-functionality, very temporary view? (And yes, I realize I could easily create this view programatically or accomplish the end goal in many different ways which would be easier, but I'm trying to really learn this stuff and I think figuring this out will help...
Thanks for the help!
You created a view controller
You accessed its view which caused controller to create the view and call the delegates (i.e. viewDidLoad)
Controller returns the view that you asked for
Now you add the view as a subview which increases its retain count
Controller is released and it releases the view, BUT since view's retain count was increased the view is still there
You try to remove the view, it is unloaded and delegates are to be called (e.g. viewDidUnload), however that messes up since the controller who created the view is released and that piece of memory is... smth else :)
That's why the first method doesn't work.
The second method is NOT correct either but it works because:
You remove controller's view from superview but since controller itself is not released (you didn't call [self release] or anything like that, not saying that you should :), just an example), then the view didn't reach 0 (zero) retain count and is still there - which means its subviews aren't removed
The proper way to do it is to save the reference to the controller as an instance variable (usually declare a synthesized property), and release it only when you are done with the view, making sure that the view is removed from superview before hand. The default templete for a View Based App shows how view controller should be managed
Hope this helps to understand why both methods behave differently
Based on your clarifications, you don't need secondView property or iVar. Also in your loadSecond instead of secontController = bla you need self.secondController = bla, otherwise you simply assign reference to the iVar instead of going through the setter.
Yes, it's possible to load subviews/other resources from a nib without having a dedicated controller
This is how you do it (one of the approaches):
UIView *result = nil;
NSArray *bundle = [[NSBundle mainBundle] loadNibNamed:#"MyNibName" owner:owner options:nil];
for ( id o in bundle ) {
if ( [o isKindOfClass:[UIView class]] ) {
result = (UIView *)o;
break;
}
}
Here the result will contain the first UIView in MyNibName. You can use other criteria to find out whether you got the view you wanted (tags, types...)
I have a navigation based iPhone app.
When you press on a cell in the tableview a new UIViewController is pushed to the navigation stack. In this view controller I am setting a custom titleView in the viewDidLoad method:
- (void)viewDidLoad {
[super viewDidLoad];
// Setup custom navigation title
[self setTitle:#"Mediaportal"];
navItem = [[NavigationBarTitleItemViewController alloc] initWithNibName:#"NavigationBarTitleItem" bundle:nil];
[navItem setTitle:[theServer name]];
[navItem setSubTitle:#""];
[self.navigationItem setTitleView:navItem.view];
…
}
Once I switch back to the RootViewController:
[self.navigationController popToRootViewControllerAnimated:YES];
the app crashes with the following error (NSZombieEnabled=YES):
*** -[CALayer retain]: message sent to deallocated instance 0x5a5fd80
From what I can see the RootViewController still tries to access the custom titleView, which was deallocated with the second view controller. Once I comment out the custom titleView part in my code the app works.
I tried to set the navigationItem.titleView to nil (as found in the apple docs) before the second ViewController is deallocated, but that doesn't help.
Do you have a hint what I can do to prevent this crash?
Thanks,
Mark.
I had this exact same error a month or so ago, exactly the same situation. It drove me NUTS.
I discovered that the viewController i was popping too hadn't been deallocated at all. I had a custom UIButton subclass added to that view however that had been deallocated when the second view had been pushed. So when popping back, the UIButton wasn't there.
Check the view you are popping back to, to ensure you've not got any classes that you are deallocating, or are being autoreleased without you knowing.
Hope this helps.
I finally found the solution for it (a quite simple one).
I have to alloc and init the navItem through its property then it is being retained:
self.navItem = [[NavigationBarTitleItemViewController alloc] initWithNibName:#"NavigationBarTitleItem" bundle:nil];