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.
Related
this question is very frequent, but I am not able to solve it with any answers available.
I am working on iOS 5.1. My navigation controller is one tab amongst tab bar view controllers. There's a tableview, in which selecting of a row pushes new view controllers.
This problem occurs Only on selecting of the second row and only sometimes. It's not regular.
The Pushed view comes blank - viewWillAppear/viewDidAppear are not being called. On clicking the back button of the navigation bar - the root view's viewWillAppear/viewDidAppear are also not being called, making it blank.
I am pushing the view on select of first row/second row in exactly the same way. But the problem occurs only on the second row.
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath{
switch (indexPath.row) {
case 0:
AViewController *aObj = [[AViewController alloc] init];
aObj.homeObj = self;
[self.navigationController pushViewController:aObj animated:YES];
[aObj release];
break;
case 1:
BViewController *bVCObj = [[BViewController alloc] init];
bVCObj.homeObj = self;
[self.navigationController pushViewController:bVCObj animated:YES];
[bVCObj release];
break;
default:
break;
}
[tableView deselectRowAtIndexPath:indexPath animated:YES];
}
I have tried this and this but in vain.
viewDidLoad is being called on pushing the BViewController, However, viewWillAppear and viewDidAppear is not being called. Following is my viewDidLoad:
- (void)viewDidLoad
{
[super viewDidLoad];
self.view.backgroundColor = [UIColor blackColor];
NSLog(#"nav stack: %#", [self.navigationController viewControllers]);
NSLog(#"nav stack: %#", [[self.navigationController visibleViewController] description]);
//some initialization and call of methods
}
It's not regular. Sometimes I get this scenario, and this continues until I close the app from the background and restart it. But sometimes it works just fine. I am just pushing my view controller to the nab stack.
As I mentioned in the comment, It's a regular navigation controller in tab bar controller.
How are you defining your views for AViewController and BViewController? Generally you'd use initWithNibName, e.g.
AViewController *aObj = [[AViewController alloc] initWithNibName:#"mynibname" bundle:nil]`
As Carl pointed out, you can apparently use just init (though I don't see this documented in the UIViewController Class Reference), but then the system will be very particular about the name of your NIB file. The documentation does say, though, that you can use initWithNibName and pass a nil for the NIB name, in which case it will try to find it for you. Personally, if you're having inconsistent results, though, I'd try using initWithNibName and explicitly pass the name of your NIB, and see if that rectifies the situation.
Or are you building your view programmatically with loadView in your two controllers? Then you need to show us those loadView routines (not to be confused with viewDidLoad).
But according to the documentation, you need to either specify your NIB or use loadView. See the View Management discussion in the UIViewController Class Reference.
Update:
Given your feedback, I have a couple of thoughts:
Needless to say, the problem is apparently not related to the above code. You need to broaden you search and show us more code. Perhaps show us your viewDidLoad of B?
Generally when you don't get these sorts of events, it's because the view controller hierarchy has gotten out of sync with the view hierarchy. The most common way that people do this is if they've done something like "[addSubview someNewController.view]" at some point. If you're using a view controller in any context either than (a) your app delegate's initial configuration; (b) presentViewController (or dismiss); or (c) pushViewController (or pop), then you might want to share what you've done.
As andreamazz pointed out, your comment, "My navigation controller is inside a view controller of the tab bar controller," is a little disturbing if one reads it literally. You can put navigation bar in a view controller's view, but you can't put a navigation controller in a view controller (unless you're doing view controller containment, which is a whole different beast). Equally concerning is where, in another one of your questions, you said, "Embedding a UINavigationController or UITabBarController (my case) in a UIViewController somehow interrupts with the calling of these methods." Thing is, you don't embed nav controllers in other view controllers (unless it is, itself, a container controller such as a tab view controller), but rather its the other way around. But if you literally mean that you have a controller that contains a nav controller, you have to show us how you're doing that (proper view controller containment?) because that's highly unusual.
It's unusual, but I've had projects get corrupted, ending up in weird states. At a minimum, I might suggest "Product" - "Clean" and rebuild. If problem persists, and you've isolated the problem to to B's NIB, then temporarily rename the it and build a quick and dirty one from scratch.
I have added following piece of code in a view.
- (IBAction)accept_clicked:(id)sender {
[self.view removeFromSuperview];
self.view = nil;
}
Once accept is clicked, I have removed the own view like this. It worked fine, anyhow is it fine to do like this or It should be removed from another view(parent)?
Don't do this (with self.view) - it doesn't looks good and you might face difficult to find problems. self.view is the main view associated with an UIViewController. So this view to be visible on the screen, you must have shown it somehow: either pushing it to a UINavigationController or presenting it modally with -presentViewController:animated:completion: (IOS5+) or - presentModalViewController:animated:. Showing a view by instantiating a view controller and adding its view to the current view controller's view is not a good practice also:
//Not good
MyViewController *mvc = [[MyViewController alloc] init];
[self.view addSubView:mvc.view];
In your particular case I suppose you are showing some terms and conditions (or something similar) and have an accept and deny button, your best solution would be to present your view controller from somewhere, implement a delegate method, so the presenting view controller can have the result and then in your -accept_clicked: method to use either [self dismissModalViewControllerAnimated:YES] or [self dismissViewControllerAnimated:completion:] (IOS5+),
I have a UITabBarController, and one tab is a UINavigationController. I have a search bar that goes to a certain view within the UINavigationController. The problem is that if the first view is not pushed by the UINavigationController, than it crashes because my search doesn't recognize the visibleViewController from this call:
UINavigationController *navController = [self.MainTab.viewControllers objectAtIndex:1];
FirstViewController *fVC = [navController visibleViewController];
What I don't understand is, before this code, I do this:
self.MainTab.selectedIndex = 1;
This code on its own selects the viewController in that tab, where then the view gets loaded to my knowledge. So shouldn't this be enough for the [navController visibleViewController] to get the current viewController? Thanks.
Try topViewController instead of visibleViewController.
FirstViewController *fVC = [navController topViewController];
From what you explain in your question and comments, I understand that your code tries to access an object of type FirstViewController, supposedly the first view to be pushed on to your UINavigationController, when it has not yet been created.
On the other hand, if you first programmatically select the tab, the view is created and everything works fine. Indeed, that view is created in a viewDidLoad method that is run when the tab is selected.
The solution I would suggest is avoiding accessing the UINavigationController visibleViewController directly from your search tab; instead, let your search code access the model (as in Model-View-Controller) for your app and store there the result; then, from the mentioned viewDidLoad method again access the model to read the search result and update/show the UI.
This is the clean solution, IMO. If you want a sort of workaround to your current design, then check the fVC value you get back from visibleViewController and if it is not what expected, then instantiate the view properly.
I hope this helps.
I know this has been answered, but I found another solution that might be helpful. In my case I was handling rotation differently for some viewControllers within my NavigationController, I did the following:
Subclass UINavigationController, then where needed in your new subclass you can access the current visibleViewController's title like so:
- (BOOL)shouldAutorotate
{
if ([[self visibleViewController].title isEqualToString:#"Special Case"]) {
return NO;
}
return YES;
}
This is not specific to rotation, this is just what I used it for. The only thing you have to do is set your self.title for each of the viewControllers you are checking against in their viewDidLoad, if they are set in IB or are not set they will be nil.
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...)
Being new to Cocoa, I'm having a few issues with Interface Builder, UIViewController and friends.
I have a UIViewController subclass with a UIView defined in a xib, and with the controller's view outlet connected to the view. The xib's "file's owner" is set as myViewcontroller subclass.
In this one instance, the following code to load the controller/view (from the main view controller) doesn't work as expected:
if ( self.myViewController == nil )
{
self.myViewController = [[MyViewController alloc]
initWithNibName:#"MyViewController" bundle:nil];
}
[self.navigationController
pushViewController:self.myViewController animated:YES];
In MyViewController's methods, I have placed breakpoints and log messages to see what is going on:
-(id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil {
if (self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil]) {
NSLog(#"initWithNibName\n");
}
return self;
}
-(void)viewDidLoad {
[super viewDidLoad];
NSLog(#"viewDidLoad\n");
}
Expected result
Both -initWithNibName and -viewDidLoad methods are called, and myViewController's view is displayed.
Observed result
Only -initWithNibName is called, the view is not displayed.
Have I missed something? Can anyone recommend anything to check? (Particularly in the wondrously opaque Interface Builder tool).
RE: SOLUTION FOUND!!!!!
Indeed that seems to be a working solution, however the real trick is not in setting the view.hidden property to NO, what makes the view load from the nib file is the calling of the UIViewController's view method, the view only actually gets loaded from the nib when the view method is called for the first time.
In that sense, a simple [viewController view] message would force the view to load from the nib file.
Ok, I have a partial answer - maybe the gurus can explain some more. The problem is:
[self.navigationController pushViewController:myViewController animated:YES];
Looking more closely, in this case self.navigationController is nil - so the push message is going no-where.
Instead, if I send:
[self.view addSubview:self.myViewController.view];
Then the view appears and -viewDidLoad is called.
I'm not entirely sure why self.navigationController is not set in this instance - the only thing I can think of is that self is a subclass of UIViewController rather than UITableViewController (where the pushViewController code came from).
Also, silently allowing messages to go to nil seems like a bad idea, although these answers say otherwise. See also my question here.
Final edit:
Answers in comments below, I've realised the display function that I was actually after (given myViewController is modal) is:
[self presentModalViewController:myViewController animated:YES];
Thanks everyone for their helpful responses.
SOLUTION FOUND!!!!!
Even something as innocuous as this makes the viewDidLoad method call happen.
Insert this right after alloc initWithNibName
viewController.view.hidden = NO; //calls viewDidLoad
make sure that the view outlet in File's Owner (your viewController subclass) is connected to the actual view (i.e. the 480X320 canvas you see on your screen that you use to build your UI)
Chances are that you might not have linked the supposed ViewController in main.storyboard from the Identity Inspector to the custom class you created. You might be able to navigate to that controller from other view controllers via segues but any of viewDidLoad(), viewWillAppear() etc. won't be executed.
Simply use
- (void)viewDidAppear:(BOOL)animated{
[super viewDidAppear:animated];
//Your Code here
}
instead of the viewDidLoad method.
Another reason, somewhat obvious in retrospect: if viewController.view is set in code, then the viewDidLoad event will not trigger.
It looks like a capitalization problem to me. You're referencing the class MyViewController instead of the property myViewController in the call to pushViewController.
Check your run log for errors. Almost certainly, the NIB is not loading, and there should be an error to that effect. The most likely cause for that is failure to put it in the bundle. Look in your "Copy Resources" build phase and make sure that the XIB is actually being copied. Build for the simulator, and go down into the build directory and make sure that the NIB is in the .app bundle.
Apart from other answers here,
It often happens when the identifier with which you instantiate your ViewController from the storyboard is incorrect. For e.g.
[[self getStoryboard] instantiateViewControllerWithIdentifier:MyVC];
If MyVC is the identifier of some other ViewController, this might happen.
OP is using nib instead of storyboard here. But the answer applies.
The page has been presented but not visible in Debug view hierarchy & in device(simulator also), issue happens based on and
i found the fix:
func viewWillLayoutSubviews{
if day == true{
self.view.backgroundColor = .clear
}else{
self.view.backgroundColor = .blue
}
}
Don't try to implement the self.view (viewcontrollers view) in function of layoutsubviews. So better use self.view in viewwillappear or viewdidload. This issue happens starts from v-14 devices.
Hope it works for you too.