I created a new window based applications. Immediately i created a class as a subclass of ViewController and in the appdelegate didFinishLaunchingWithOptions method i've added the following code
TestView myView = [[TestView alloc] initWithNibName:nil bundle:nil];
[self.window makeKeyAndVisible];
[self.window addSubview:mainMenu.view];
[mainMenu release]
However, despite this it still initializes the nib. If i placed a button in TestView.xib it shouldn't technically show it right? I initialized TestView without a nib? Why does it show up?
If you pass nil to -initWithNibName:bundle:, it will attempt to load a nib from the main bundle that has a filename that matches the name of the subclass, or the name of the subclass without the "Controller" suffix.
If you dont want it from a nib you should not init it in this way, it will still search for a xib that matches the class name exactly.
From the apple documentation found here:
http://developer.apple.com/library/ios/#documentation/uikit/reference/UIViewController_Class/Reference/Reference.html
If you specify nil for the nibName parameter, you must either override the loadView method and create your views there or you must provide a nib file in your bundle whose name (without the .nib extension) matches the name of your view controller class. (In this latter case, the class name becomes the name stored in the nibName property.) If you do none of these, the view controller will be unable to load its view.
Related
I have a UIViewController subclass which I am instantiating and trying to push on to the navigationController like so :
MenuVC *menuVC = [[MenuVC alloc] init];
[self.navigationController pushViewController:menuVC animated:YES];
I don't have a nib file associated with this class and so just doing a simple ..alloc] init] instead of initWithNib:bundle:.
I am still getting a crash on the pushViewController call and the trace says this
reason: '-[UIViewController _loadViewFromNibNamed:bundle:] loaded the "MenuVC" nib but the view outlet was not set.'
I don't see why this could be happening. I have other view controller which loads fine with the same method.
I think I found the answer to this in Apple's Docs :
A view controller has an associated nib file if the nibName property returns a non-nil value, which occurs if the view controller was instantiated from a storyboard, if you explicitly assigned it a nib file using the initWithNibName:bundle: method, or if iOS finds a nib file in the app bundle with a name based on the view controller’s class name.
So, this means the OS actually tries to load the nib if it finds one. I did have a nib in my bundle with same name as VC but had not associated it's File Owner.
The real problem is that the Viewcontroller have a view that comes in default and somehow that connection of IB to class view->view went missing and hence the error
This might not be an "answer" but this was resolved. I just removed the whole file and added a new file with a different name and it worked.
I made a XIB that only consisted of a UITableView in IB. It was brought to my attention that it is possible to subclass UITableViewController and do away with the xib entirely.
My question is, how do you do this?
So far the only thing I have changed is my .h to be...
#interface MyView : UITableViewController
and removed my XIB. Obviously I get an error that states
*** Terminating app due to uncaught exception 'NSInternalInconsistencyException',
reason: 'Could not load NIB in bundle: 'NSBundle (loaded)' with <path>
name 'MyView''
so my question is, what else is left in order to accomplish this subclassing correctly?
There are two ways to set up your view controller in iOS.
With a .xib file: You instantiate the view controller with -initWithNibName:bundle:, passing the name of your .xib file as the first argument, and (unless you're doing some advanced stuff) nil as the second argument . The OS will look for your .xib file and unserialize it into a bunch of objects and attach them to your view controller. Then the OS calls your view controller subclass's -viewDidLoad: method, where you finish setting things up.
Programmatically: You instantiate the view controller with -init, or for a table view controller, initWithStyle:. The OS then calls your subclass's -loadView method, where you manually instantiate your view hierarchy.
It sounds like you just need to instantiate it with -initWithStyle: instead of -initWithNibName:bundle:.
If you had a ViewController without a .xib you could just create a tableview in the view did load or something.
UITableView *table = [[[UITableView alloc] initWithStyle:UITableViewStylePlain] autorelease];
table.dataSource = self;
table.delegate = self;
table.frame = CGRectMake(0, 10, self.view.frame.size.width, self.view.frame.size.height);
[self.view addSubview:table];
And then you just need to implement the proper delegate and data source methods like you would in a UITableViewController.
I tried looking for a similar problem but I could not find a similar question.
I am loading a UINavigationController in a UIView which is not (as in most examples) the MainWindow.
I created one new .xib called DocumentsViewController which is subclass of UIView (it has the related .m and .h files). And I created a DocumentsRootViewController.xib, which is a subclass of UITableViewController, which is supposed to be the UINavigationController's RootViewController.
I moved to DocumentsViewController and added a UINavigationController object in Interface Builder. Then I went to code, and added it as in IBOutlet, and connected it to the object.
In the ViewDidLoad, I execute the following lines:
DocumentsRootViewController *rootViewController = [[[DocumentsRootViewController alloc] init] autorelease];
rootViewController.title = #"Documents";
[navigationControllerDocuments initWithRootViewController:rootViewController];
[self.view addSubview:navigationControllerDocuments.view];
It shows the table as intended, but it shows a "Back" button to the "Root View Controller" (as in picture below).
Why? Shouldn't it already know that the rootviewcontroller has been set?
Thank you in advance to the ones that clarify this doubt
Giovanni
When you add the UINavigationController via the Nib it actually creates an instance of a UINavigationController inside the nib file with a default RootViewController set (of type UIViewController) and with a default title of RootViewController.
When you load the nib, this object is being created as part of loading the nib (i.e when you initialise DocumentsViewController) - so the navigationControllerDocuments outlet is already initialised as a UINavigationController with the default ViewController already set on it.
What I think is happening is when you call 'initWithRootViewController' - you are calling this on an already initialised object - so it is running the initialisation code again - pushing the second view controller (the DocumentRootViewController) onto the stack, but the default one that was created in the nib is already there.
What you should probably do is forget about creating one in the nib and initialise the whole thing programatically.
i.e. where you do:
[navigationControllerDocuments initWithRootViewController:rootViewController];
I suggest that you do an alloc and init instead:
[[navigationControllerDocuments alloc] initWithRootViewController:rootViewController];
Since you are doing this you really don't need to have the navigation controller added to the nib so if this works you should remove it from the nib since you are replacing it with this one in code.
How do I prevent a UIVIewController from loading the xib?
I downloaded an XCode (iPhone) project online, and I want to stop the xib file from loading. The view did load method doesn't have any code in it which deals with xib. How do I force the UIViewController to be loaded from it's viewDidLoad method instead of the xib?
Overwrite loadview but DO NOT call [super loadview]. Example:
-(void)loadView{
self.view = [UIView new];
[self.view setBackgroundColor:[UIColor redColor]];
}
From the Documentation
loadView
Creates the view that the controller manages.
You should never call this method
directly. The view controller calls this method when the view property
is requested but is currently nil. If you create your views manually,
you must override this method and use it to create your views. If you
use Interface Builder to create your views and initialize the view
controller—that is, you initialize the view using the
initWithNibName:bundle: method, set the nibName and nibBundle
properties directly, or create both your views and view controller in
Interface Builder—then you must not override this method.
The default implementation of this method looks for valid nib
information and uses that information to load the associated nib file.
If no nib information is specified, the default implementation creates
a plain UIView object and makes it the main view.
If you override this method in order to create your views manually,
you should do so and assign the root view of your hierarchy to the
view property. (The views you create should be unique instances and
should not be shared with any other view controller object.) Your
custom implementation of this method should not call super.
If you want to perform any additional initialization of your views, do
so in the viewDidLoad method. In iOS 3.0 and later, you should also
override the viewDidUnload method to release any references to the
view or its contents.
Write your own init method. Later if you require the nib you can create a UINib object and when you need the view you can use instantiateWithOwner.
Using init when creating your view controller will prevent the nib loading. Another thing to do is to name the nib something other than the name of the view controller - because the nib can be loaded automatically if they match. I use ViewControllerName_iPad or ViewControllerName_iPhone and create the view required depending on device idiom.
The code to load from the xib file is not in the viewDidLoad method of the view controller itself.
You should usually find it in the application delegate's didFinishLaunchingWithOptions: method, or in the info.plist file, under the NSMainNibFile entry.
Try changing the initWithNibNameOrNil method to just init.
If that doesn't work, also override the loadView method by uncommenting it and setting your view there.
Here's an example:
- (id)init
{
self = [super init];
if (self) {
// Custom initialization
}
return self;
}
- (void)loadView {
[super loadView];
UIView *myView = [[UIView alloc] initWithFrame:CGRectMake(0,0,320,460)];
myView.backgroundColor = [UIColor redColor];
self.view = myView;
[myView release];
}
Perhaps I'm barking up the wrong tree here, but is the UIViewController loading its view from a XIB because the XIB that loads the UIViewController itself has a "NIB Name" set in the view controller's settings?
e.g. load up MainWindow.xib, see your view controller. Select it, then look in the view controller settings over on the right (4th tab). One of the settings is "NIB Name". Just make that blank to stop the view controller loading its view from that XIB/NIB.
I know there is a seemingly exact duplicate of this question here: iPhone SDK: what is the difference between loadView and viewDidLoad?
However, I have read that question and still it was not fully answered.
I'm not using IB as the UI is dynamic.
So should I create the self.view and then add the subviews in loadView,
or should I create the self.view in loadView and add the subviews in viewDidLoad?
When you load your view from a NIB and want to perform further customization after launch, use viewDidLoad.
If you want to create your view programatically (not using Interface Builder), use loadView.
For your specific question, you should add the subview in viewDidLoad. Because, if you overwrite the loadView, you have to do all the jobs, loading all the views.
Here is the explanation from Apple's documentation:
The steps that occur during the load cycle are as follows:
1.
* Some part of your application asks for the view in the view
controller’s view property.
2.
* If the view is not currently in memory, the view controller calls its loadView
method.
3.
* The loadView method does one of the following:
If you override this method, your implementation is
responsible for creating all
necessary views and assigning a
non-nil value to the view property.
If you do not override this method, the default implementation uses
the nibName and nibBundle properties of the view controller to try to load the view
from the specified nib file. If the
specified nib file is not found, it
looks for a nib file whose name
matches the name of the view
controller class and loads that file.
If no nib file is available, the method creates an empty UIView object
and assigns it to the view property.
4.
* The view controller calls its viewDidLoad method to perform any
additional load-time tasks.
It is very simple actually. If you do it without IB, then your UIViewController's view property is empty. So set it at loadView!
I only do setting of view at loadView and nothing else.
Other than that, do all thing inside viewDidLoad. Here is some example:
- (void)loadView {
CGRect frame = [[UIScreen mainScreen] applicationFrame];
baseView = [[UIView alloc] initWithFrame:frame];
[self setView:baseView];
[baseView release];
}
That's it! I am done. And would never want to add more to it. Then at the viewDidLoad, I add all those subviews I want to.
- (void)viewDidLoad {
[super viewDidLoad];
msg = [[UILabel alloc] initWithFrame:CGRectMake(0, 200, 320, 50)];
[msg setText:#"Your profile is empty!"];
[[self view] addSubview:msg]; // hey, I have done my view at loadView, so I have it now
[msg release];
}
I could be wrong in my understanding :)
loadView is the method that actually sets up your view (sets up all the outlets, including self.view).
viewDidLoad you can figure out by its name. It's a delegate method called after the view has been loaded (all the outlets have been set) that just notifies the controller that it can now start using the outlets.
viewDidLoad:
"This method is called after the view controller has loaded its associated views into memory. This method is called regardless of whether the views were stored in a nib file or created programmatically in the loadView method."
loadView:
"If you create your views manually, you must override this method and use it to create your views."
Add subviews in viewDidLoad. That way you are 100% sure than the view did indeed load and is ready for consumption.
Use viewDidLoad for initialize views and constrols. And use loadView if you don't have Nib/Xib and would like your ViewController has custom (not UIView) view.
Only use loadView when you want to create a view yourself.
Don't use loadView after you use interface builder or init with nib since these actions have already called loadView in the underly implementation.
Also, when use loadView, assign view first before doing any other settings:
-(void)loadView {
[super loadView];
// if you do any things here before assigning a view
// it will try to get a view first by calling loadView()
// and ends up with a crash since a dead loop.
self.view = ...;//assign your view here
//do other settings
}