I am trying to work my way through basic iPhone programming and I have a good basic understanding of how Interface Builder works, so I decided to try my hand at doing the views programmatically. I have gone through the ViewController Apple guide and searched everywhere and I cannot seem to find a solution to my problem. This leads me to believe it is a very simple solution, but I am just really banging my head against the wall. Basically all I am trying to do is create a view that gets main window as a subview. I know that if self.view is not defined then the loadView method is supposed to be called, and everything is supposed to be set up there. Here is the current state of my code:
The delegate:
- (void)applicationDidFinishLaunching:(UIApplication *)application {
StartMenuViewController *aViewController = [[StartMenuViewController alloc] init];
self.myViewController = aViewController;
[aViewController release];
UIView *controllersView = [myViewController view];
window = [[UIWindow alloc] initWithFrame:[UIScreen mainScreen].bounds];
[window setBackgroundColor:[UIColor redColor]];
[window addSubview:controllersView];
[window makeKeyAndVisible];
}
The view controller:
- (id)init {
if (self = [super init]) {
self.title = #"Start Menu";
}
return self;
}
// Implement loadView to create a view hierarchy programmatically, without using a nib.
- (void)loadView {
UIView *startView = [[UIView alloc] initWithFrame:[UIScreen mainScreen].applicationFrame];
[startView setAutoresizingMask:UIViewAutoresizingFlexibleHeight|UIViewAutoresizingFlexibleWidth];
[startView setBackgroundColor:[UIColor greenColor]];
self.view = startView;
[startView release];
}
Thanks for the help in advance!
Are you sure that you're inheriting from UIViewController and not overriding the implementation of - (UIView*)view?
EDIT: More info:
UIViewController has a special implementation of the "-(UIView*) view" message so that when it's called, the loadView method is called if the view member variable is not set. So, if you provide an implementation of "- (id)view" in your subclass, (or a property named view) it will break the auto-calling of "- loadView".
Just to document a "loadView is not called" case:
I wrote a 2 UITableViewController(s) to handle detail data for a master ViewController. Since the devil was in #2, I made a simple UITableViewController for #1, and referenced it in the XIB for the "master" ViewController.
When I was done with #2, I could simply copy the code to #1, remove the complicated code, and go on with life.
But to my dismay and several days work, no matter what I did, viewLoad was not being called for my simple #1 UITableViewController.
Today I finally realised that I was referencing the UITableViewController in the XIB to the master ViewController program. - and of course, loadView was never being called.
Just to help some other dork that makes the same mistake....
Best Regards,
Charles
viewDidLoad only if the view is unarchived from a nib, method is invoked after view is set.
loadView only invoked when the view proberty is nil. use when creating views programmatically. default: create a UIView object with no subviews.
(void)loadView {
UIView *view = [[UIView alloc] initWithFrame:[UIScreen
mainScreen].applicationFrame];
[view setBackgroundColor:_color];
self.view = view;
[view release];
}
By implementing the loadView method, you hook into the default memory management behavior. If memory is low, a view controller may receive the didReceiveMemoryWarning message. The default implementation checks to see if the view is in use. If its view is not in the view hierarchy and the view controller implements the loadView method, its view is released. Later when the view is needed, the loadView method is invoked
again to create the view.
I would strongly recommend you use interface builder for at least your initial Window/View.
If you create a new project in XCode you should be able to select from one of many pre-defined iPhone templates that come with everything setup.
Unless I am reading this wrong, you did not associate any view with the the controller's view property like this
myViewController.view = controllersView;
So as far as Cocoa is concerned the view you are setting in the window has no controller to call loadView on. loadView is a View controller, not view, method. The view you assign to the window is not associated with any view controller. So your view controller loadView method is never called. Get it? The view you are trying to display, has no view controller associated with it.
When you use interface builder to create views you can link the UIView object you created in IB to the view property in the controller in IB which the framework automatically
But if not done in IB you have to set it
Related
Two objective-c methods, -(void) viewDidLoad and -(void)loadView are methods called upon execution of a program but whats the different between them?
Do you mean viewDidLoad and loadView? viewDidLoad is a method called when your view has been fully loaded. That means all your IBOutlets are connected and you can make changes to labels, text fields, etc.
loadView is a method called if you're (typically) not loading from a nib. You can use this method to set up your view controller's view completely in code and avoid interface builder altogether.
You'll typically want to avoid loadView and stick to viewDidLoad.
Use -(void)loadView when you create the view. Typically usage is:
-(void)loadView {
UIView *justCreatedView = <Create view>;
self.view = justCreatedView;
}
Use -(void)viewDidLoad when you customize the appearance of view. Exapmle:
-(void)viewDidLoad {
self.view.backgroundColor = [UIColor blackColor];
...
}
i think you are talking about loadView and viewDidLoad.
loadView is a method that you not using a nib file - you use it to programmatically 'write' your interface
viewDidLoad fires automatically when the view is fully loaded. you can then start interacting with it.
more to read read in the discussion here iPhone SDK: what is the difference between loadView and viewDidLoad?
I am building a cocoa application with one main window controller with a xib. That xib contains many custom view classes. I would like to add an NSViewController to the xib, but i'm running into some trouble.
In interface builder I can drag the NSViewController into the xib, assign it its custom controller class, and assign its view to the appropriate view in the xib. Here's the problem: neither the initWithNibName:Bundle: or loadView get called.
What am I missing?
EDIT:
People seem to be misunderstanding the question so I'll clarify.
The window already has a view controller. What I am seeking to do is assign separate view controllers to several of the subviews. I need to know how to associate my NSViewController subclass with the appropriate NSView subclass (which is a child of the main window).
Or in other words, I am trying to use multiple NSViewController subclasses to controll many different custom views (one each) within a single .xib file. Those controllers and subviews have their own .xibs which should ultimately become visible in the same window.
The pattern I use for NSViewController is to have a xib per view controller. Then, when you need that view controller you alloc it and use the initWithNibName:Bundle: method. As soon as you use its view, loadView will get called.
Example:
self.editViewController = [[[MyEditViewController alloc] initWithNibName:#"MyEditViewController" bundle: nil] autorelease];
[self.window setContentView: editViewController.view];
I used to get stuck with that as well and gave up on that thing - the blue circle with a white bordered view in it from the IB palette. I now create my controllers from code and only set a reference in IB to the owning controller class via the file owner: right click the file owner, enter the class name in the Identity inspector and then make a connection from the file's owner view to the view.
In your code you then do at an appropriate initialisation point:
[self setMyViewController = [[MyViewController alloc] initWithNibName: #"MyView" bundle: [NSBundle mainBundle]]
For your specific case this could be in windowDidLoad method when your window is loaded from its nib and ready for work. You can then add the view to your windows content view. Also you might want to consider to have a 1:1 relation between view and view controller. It makes life a lot easier in terms of maintenance.
EDIT: Like #pcperini suggests in his comments you can use the palette component, but you'll still need to instantiate the controller in your code. If you want to use the palette component, create a property in your main controller or AppDelegate:
#property (...) MyViewController *myViewController;
Add the line of code to actually create the controller (see above). Then, using the bindings inspector bind the palette component to the myViewController property.
So, what you are missing is that you are actually not instantiating the controller object.
EDIT 2: Here's the code (the awakeFromNib is the method of the top controller). It creates two child controllers each handling a different subview:
- (void) awakeFromNib {
[[self startEndTopicHeader] setHeader: #"Event timeline boundary"];
[[self startDateHeaderView] setHeader: #"Event (start) date"];
[[self endDateHeaderView] setHeader: #"Event end date"];
[self setStartDateViewController: [[EventTimeViewController alloc] initWithNibName: #"EventTimeView" bundle: [NSBundle mainBundle]]];
[[[self startDateViewController] view] setFrame: [[self dummyStartView] bounds]];
[[self dummyStartView] addSubview: [[self startDateViewController] view]];
[[self startDateViewController] setParentController: self];
[self setEndDateViewController: [[EventTimeViewController alloc] initWithNibName: #"EventTimeView" bundle: [NSBundle mainBundle]]];
[[[self endDateViewController] view] setFrame: [[self dummyEndView] bounds]];
[[self dummyEndView] addSubview: [[self endDateViewController] view]];
[[self endDateViewController] setParentController: self];
}
Lets say that I have 4 view controllers (call them FirstView,SecondView,ThirdView,FourthView) which are created programmatically and all are in separate files:
In AppDelegate.m didFinishLaunchingWithOptions method I have these lines of code
self.rootViewController = [[rootViewController alloc]initWithNibName:#"rootViewController" bundle:nil];
self.window.rootViewController = self.rootViewController;
In rootViewController.m loadview method I have
self.view = [[UIView alloc]initWithFrame:[UIScreen mainScreen].applicationFrame];
self.firstView = [[FirstView alloc]init];
[self.view addSubview:self.firstView.view];
That code works fine - first view is displayed.
Let's continue
In FirstView.m switchViews method
NOTE: Please see the comments in code
self.secondView = [[SecondView alloc] initWithNibName:#"SecondView" bundle:nil];
// I think here secondView is added to rootViewController - right ?
[self.view.superview addSubview:self.secondView.view];
// Here first view is removed from rootViewController - right ?
[self.view removeFromSuperview];
Here is how I add/remove views.
Is this approach correct?
Can you recommend a better solution?
I have read about UINavigationController, but I don't think it could be a solution in this case.
You say:
I have 4 views (call them FirstView ...
Then you say:
[self.view addSubview:self.firstView.view];
Which makes me think that FirstView isn't actually a UIView - as you claim it is. Instead, it's probably a UIViewController - a different beast altogether.
If my suspicion is correct - then you are "off-track" so to speak.
Going beyond that to your sample code snippet:
self.secondView = [[SecondView alloc] initWithNibName:#"SecondView" bundle:nil];
// I think here secondView is added to rootViewController - right ?
[self.view.superview addSubview:self.secondView.view];
// Here first view is removed from rootViewController - right ?
[self.view removeFromSuperview];
This is definitely not a great idea. Here's why:
First: your view controller doesn't explicitly "know" anything about the superview you are so casually inserting and removing subviews to/from - so it shouldn't do that. You may, alternatively, create your own view and insert/remove subviews from that - which would not only be perfectly acceptable but also common practice.
Second: if these are actually UIViewControllers like I think they are - then you are not properly handling hooking them up to the UIViewController event chain - which means methods on these subclasses like viewDidAppear: or viewDidUnload will not fire.
From what I see in your code, UINavigationController seems like it would help. If you don't want a navigation bar, you can definitely hide it, but the methods in UINavigationController should help you with switching views.
If your views only need to display temporarily, you could also use Modal View controllers. An example of Modal View controllers can be found here.
If you haven't already, check out the View Controller Programming Guide from Apple.
I set views programmatically. Here is how I do that. Let's say I have SettingsViewController.m
In this file I have two methods
-(void)loadView
{
UIView *view = [[UIView alloc] initWithFrame:[UIScreen mainScreen].applicationFrame];
self.view = view;
[view release];
}
-(void)didViewLoad
{
// In that method I create some buttons labels etc
}
Is my approach correct ? To create the view in loadView method and buttons, labels etc in viewDidLoad method
To be honest it doesn't really matter if you put the code for creating views in viewDidLoad or loadView. viewDidLoad is called after the view is loaded, so will even be called if you are instantiating from a XIB. So that's a good place to add extra views if you're using a XIB. If you're programatically creating the view like you are in loadView then you can put the creation of your buttons, labels, etc in loadView or viewDidLoad and it won't really make a difference - viewDidLoad is pretty much called straight after loadView runs anyway.
Personally if I'm creating a view programatically using loadView then I will put all of the view creation code in there rather than in viewDidLoad.
I have a UIViewController subclass that contains an instance of UIImagePickerController. Let's call this controller CameraController. Among other things, the CameraController manages the UIImagePickerController instance's overlayView, and other views, buttons, labels etc. that are displayed when the UIImagePickerController, let's call this instance photoPicker, is displayed as the modal controller.
The photoPicker's camera overlay and the elemets that are part of the CameraController view hierarchy display and function as expected. The problem I'm having is that I cannot use UIViewController's default initializer to create the CameraController's view heirarchy.
I am initializing CameraController from within another UIViewController. Let's call this controller the WebViewController. When the user clicks on a button in a view managed by WebViewController, the launchCamera method is called. It currently looks like this:
- (void) launchCamera{
if (!cameraController) {
cameraController = [[CameraController alloc] init];
// cameraController = [[CameraController alloc] initWithNibName:#"CameraController"
// bundle:[NSBundle mainBundle]];
cameraController.delegate = self;
}
[self presentModalViewController:cameraController.photoPicker animated:NO];
}
I want to be able to create CameraController by calling initWithNibName:bundle: but it's not working
as I'll explain.
CameraController's init method looks like this:
- (id) init {
if (self == [super init]) {
// Create and configure the image picker here...
// Load the UI elements for the camera overlay.
nibContents = [[NSBundle mainBundle] loadNibNamed:#"CameraController" owner:self options:nil];
[nibContents retain];
photoPicker.cameraOverlayView = overlay;
// More initialization code here...
}
return self;
}
The only way I can get the elements to load from the CameraController.xib file is to call loadNibNamed:owner:options:. Otherwise the camera takes over but no overlay nor other view components are displayed. It appears that a side-effect of this problem is that none of the view management methods on CameraController are ever called, like viewDidLoad, viewDidAppear etc.
However, all outlets defined in the nib seem to be working. For example, when the camera loads a view is displayed with some instructions for the user. On this view is a button to dismiss it. The button is declared in CameraController along with the method that is called that dismisses this instructions view. It is all wired together through the nib and works great. Furthermore, the button to take a picture is on the view that servers as photoPicker's overlay. This button and the method that is called when it's pressed is managed by CameraController and all wired up in the nib. It works fine too.
So what am I missing? Why can't I use UIViewController's default initializer to create the CameraController instance. And, why are none of CameraController's view mangement methods ever called.
Thanks.
Your problem is easy but need some steps.
Well... First, if overlay is an IBOutlet, it can not be loaded at init time. So move picker and co in viewDidLoad. Place also here all other items that your say that they are not loaded. They should be loaded there (viewDIDLoad). Check that outlets are connected.
Second, call
cameraController = [[CameraController alloc] initWithNibName:#"CameraController"
bundle:nil];
and ensure that CameraController contains (just) a view, and CameraController inherits UIViewController. Check also file's owner.
And at some time, you may consider that calling :
[self presentModalViewController:cameraController.photoPicker animated:NO];
does not make the CameraController control your picker. Does that make sense to you ?
What does that do regarding your problem ?
It seems you are confusing some things. I try to explain in another way :
The one that controls the picker is the one that is its delegate. Your may consider creating in a MAIN view.
The controller of the overlay (added as subview) is the one that own its view in File's Owner. That may be created from the MAIN view, adding its view as subview of the controller. Basically, it is loaded just to get the overlay, but viewDidLoad, ... won't be called.
That's all and I belive those steps are not ok in your code.
That should give something like :
MainController
Loadcamera {
self.picker = [UIImagePicker alloc] init.....];
self.picker.delegate = self;
SecondController* scnd = [[SecondController alloc] initWithNibName:#"SecondController" bundle:nil];
[self.picker addOverlay:scnd.view];
[self presentModalViewController:self.picker animated:NO];
}
/// And here manage your picker delegate methods
SecondController
// Here manage your IBActions and whatever you want for the overlay