in the case of say
- (void)applicationDidFinishLaunching:(UIApplication *)application {
...
[window addSubview:gameController.view];
...
}
how does the view of gameController retain association to gameController? I've peaked through all of the Debugger variables and I see no association other than a boolean flag that it belongs to a view controller. so the view is passed along to a view hierarchy (wouldn't necessarily have to be off of window), yet gameController will get events such as shouldAutorotateToInterfaceOrientation . Where is this being kept track of if not as some tucked away reference in the UIView passed out of gameController.view
UIView *tmp = gameController.view;
[window addSubview:tmp];
Its obvious that gameController knows about tmp, but how does the window know about gameController after that code?
UIViewController is a descendant of UIResponder and is inserted into the responder chain between the view and that view's superview. So calling nextResponder on a view managed by a UIViewController will return said instance of UIViewController.
This is how events such as shouldAutorotateToInterfaceOrientation: get passed up through the hierarchy of instances of UIResponder. A diagram showing this can be seen in figure 3.1 in the iPhone Application Programming Guide.
Related
I want to make my code more modular and flexible.
So rather than setting a the tableViewDelegate as the UIViewController, I have a subclass of UITableViewController as the tableView data source and delegate.
Basically, the original UIViewController provides the view for the subclass of UITableViewController.
That way similar tables can be used by several UIViewController's subclasses.
In some cases, UIViewController's provide the tableView and I just switch the tableView delegate at run time.
Works well.
Here is the code for BGTableViewDelegateMother that inherits from UITableViewController (that inherits from UIViewController.
#implementation BGTableViewDelegateMother
-(void) setDelegate:(id<BGTableViewDelegateMother>)delegate
{
_delegate=delegate;
self.view = self.delegate.tvDelegated; //So that viewWillAppear would work fine
[self view]; //load the view view didload is not called either
self.delegate.tvDelegated.delegate =self;
self.delegate.tvDelegated.dataSource=self;
}
Okay. The UITableViewController.view is used for one thing. Now that it points to the correct tableView, I expect viewWillAppear to be called. It's not
I think everytime the tableView will be shown, I should at least reloadData
-(void) viewWillAppear:(BOOL)animated
{
[super viewWillAppear:animated];//never called
[self.delegate.tvDelegated reloadData];
}
This code never called. Even though the view will indeed appear. Why?
viewDidLoad is also never called.
Make the table view controller a child view controller of your view controller while its view is linked (and it is the data source) and could be on screen. This tells the view controller hierarchy that the table view needs to know about the appearance callbacks.
Is it possible to embed (add as subview) a UITableViewController into another View Controller programmatically? I found a few answers here on StackOverflow but none worked for me with ARC and iOS6 SDK.
I know you can do this easily with Navigation and TabBar controllers but I am more curious about adding tableviews to a regular View controller. I need my tableview to occupy the lower part of the available screen space (I need the rest for other purposes, for which neither tab nor navigation types are suitable).
When I tried to do it, however, it did not work. I instantiated a subclassed UITableViewController, but when I added it to my self.view as a subview, the compiler said I tried to use "incompatible pointer types." Not only that, my instantiated UITableViewController does not have a .frame property, so I cannot set it dimensions, which would be the whole point of this exercise.
Building upon ogres answer, you should add the tableViewController's view as a subview, but it is not everything. The tableViewController is a viewController and it needs to know its parent and its children, to do its viewController-job correctly. I do not know any details here, but there is an entire talk about this from WWDC 2011 called "Implementing UIViewController Containment".
One problem I have experienced when only adding the view as a subview is that target actions don't seem to work. Tapping a UIButton or similar causes either a EXC_BAD_ACCESS or a unrecognized selector sent to instance.
So I recommend that you do something like this:
UIViewController *vc = //Your tableViewController
[self addChildViewController:vc]; //Important
[self.view addSubview:vc.view];
//If you want to set the frame, set the frame of the tableViewController's view
vc.view.frame = ...
yes , you can use tableview in another view without any problems
UITableViewController, but when I added it to my self.view as a subview
are you trying to add viewcontroller as subview or its view ? ( viewcontroller.view )
UITableViewController does not have a .frame property,
of course it does not have .frame property , it is a view CONTROLLER , you should see .view.frame
If you add a subview to a view or add a view to a window, how does iOS know which controller this view belongs too?
Easy example:
Have a UIView without UIViewController and add it to the window [window addSubView:myView] --> it will not rotate.
Now use a UIViewController, have it implement shouldAutoRotateToInterfaceOrientation: and add the controller's view to the window: [window addSubView:myController.view] --> magically, the view will adjust to interface orientation.
But look at the code: in both cases a UIView was added. How can iOS possibly be aware that in the second case a UIViewController was involved?
I'm interested in how this is done internally. My best guess is that UIViewController.view is a setter which adds the controller to an internal array of controllers or assigns itself to some internal variable which holds the currently active controller.
Simple. Look in UIView.h. It's right there. Each UIView has a pointer back to a UIViewController (which is apparently referred to as the "viewDelegate").
Dave DeLong is correct (and gets +1) as it is clearly defined UIView.h as #package so anything in UIKit can access it.
Here is an example of accessing that variable for educational purposes only (obviously you will not do this in a real application).
SomeAppDelegate.m
#synthesize navigationController=_navigationController;
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
// Override point for customization after application launch.
// Add the navigation controller's view to the window and display.
self.window.rootViewController = self.navigationController;
[self.window makeKeyAndVisible];
//DO NOT TRY THIS AT HOME
UIView *mynavview = self.navigationController.view;
//Guaranteed _viewDelegate atleast in iOS 4.3
Ivar ivar = class_getInstanceVariable([UIView class], "_viewDelegate");
UIViewController *controller = object_getIvar(mynavview, ivar);
NSLog(#"controller = self.navigationController? %#", controller == self.navigationController ? #"Yes" : #"No");
return YES;
}
UIViewController has a private class method (called controllerForView:, I believe) which is used to find the view's controller. Internally, there is probably a table used to connect the two together, and this method simply finds the proper location in that table and returns its value. When the result is nil, the default implementation will be used (don't rotate).
If you want to be sure about the name of the method, set a breakpoint in -[UIView becomeFirstResponder], tap on a text field, and step through the code until it shows up in the call stack. I suggest using becomeFirstResponder because it is easier to control than most things which get the view controller.
I might be confused here and asking the wrong question.
If I use a class like the UISplitViewController inside the appdelete.m, will the only message i will receive is the message the UISplitViewController calls and not any VIEW message? for example:
in my myappdelegate.m
....
UISplitViewController *mySplitViewController = [[UISplitViewController alloc] init];
mySplitViewController.viewControllers = [NSArray arrayWithObjects:leftside,rightside,nil];
...
mySplitViewController.delegate = self;
....
[windows addSubView:mySplitViewController.view];
....
-(void) viewWillAppear:(BOOL) animated {
}
in myappdelegate.h I included UISplitViewControllerDelegate
I expected viewWillAppear to fire but it is not. I assume if I had subclass UISplitViewControler it would have fire. right?
BTW: I am doing this without using IB. Do I need to set the target for the mySplitViewController?
What I want to do is setup the orientation of the splitviewcontroller when it rotates.
the viewWillAppear method and other view related methods will be called on the view or view controller themselves, not on the delegate.
That means that if you make a subclass of UISplitViewController called SplitViewControllerSubClass, the view... methods will be called on the instance of SplitViewControllerSubClass, not on the delegate object.
But considering you are creating the views and displaying them programmatically, you already know exactly when the view will appear (i.e., right before you add it to the window), so I believe you could do whatever setup you want at that point.
I'm designing a simple Quiz application. The application needs to display different types of QuizQuestions. Each type of QuizQuestion has a distinct behavior and UI.
The user interface will be something like this:
alt text http://dl.getdropbox.com/u/907284/Picture%201.png
I would like to be able to design each type of QuizQuestion in Interface Builder.
For example, a MultipleChoiceQuizQuestion would look like this:
alt text http://dl.getdropbox.com/u/907284/Picture%202.png
Originally, I planned to make the QuizQuestion class a UIViewController. However, I read in the Apple documentation that UIViewControllers should only be used to display an entire page.
Therefore, I made my QuizController (which manages the entire screen e.g. prev/next buttons) a UIViewController and my QuizQuestion class a subclass of UIView.
However, to load this UIView (created in IB), I must[1] do the following in my constructor:
//MultipleQuizQuestion.m
+(id)createInstance {
UIViewController *useless = [[UIViewController alloc] initWithNibName:#"MultipleQuizQuestion" bundle:nil];
UIView *view = [[useless.view retain] autorelease];
[useless release];
return view; // probably has a memory leak or something
}
This type of access does not seem to be standard or object-oriented. Is this type of code normal/acceptable? Or did I make a poor choice somewhere in my design?
Thankyou,
edit (for clarity): I'd like to have a separate class to control the multipleChoiceView...like a ViewController but apparently that's only for entire windows. Maybe I should make a MultipleChoiceViewManager (not controller!) and set the File's Owner to that instead?
You're on the right track. In your QuizController xib, you can create separate views by dragging them to the xib's main window rather than to the QuizController's main view. Then you can design each view you need according to your question types. When the user taps next or previous, remove the previous view and load the view you need based on your question type using -addSubview on the view controller's main view and keep track of which subview is currently showing. Trying something like this:
[currentView removeFromSuperView];
switch(questionType)
{
case kMultipleChoice:
[[self view] addSubview:multipleChoiceView];
currentView = multipleChoiceView;
break;
case kOpenEnded:
[[self view] addSubview:openEndedView];
currentView = openEndedView;
break;
// etc.
}
Where multipleChoice view and openEndedView are UIView outlets in your QuizController connected to the views you designed in IB. You may need to mess with the position of your view within the parent view before you add it to get it to display in the right place, but you can do this with calls to -setBounds/-setFrame and/or -setCenter on the UIView.
Yeah, IB on iPhone really wants File's Owner to be a UIViewController subclass, which makes what you want to a bit tricky. What you can do is load the nib against an existing UIViewController instead of instantiating one using the nib:
#implementation QuizController
- (void) loadCustomViewFromNib:(NSString *)viewNibName {
(void)[[NSBundle mainBundle] loadNibNamed:viewNibName owner:self options:nil];
}
#end
That will cause the runtime to load the nib, but rather than creating a new view controller to connect the actions and outlets it will use what you pass in as owner. Since we pass self in the view defined in that nib will be attached to whatever IBOutlet you have it assigned to after the call.