i may be making more out of this because of the late hour. i am confused. i have multiple views i call from a viewcontroller class. typically they are called with a uibutton object. say i have two views. main and child view. here is how i would call the child while the main view is visible.
[self presentModalViewController:childViewController animated:YES];
now because i want to use touch events to call the child view i believe i am forced to initiate the events from with the main view's class.
so how do i call the child view from within the main view class as i would when i am in the view controller class.
thanks for any help!!
If I understand you correctly, you're wondering if you need to handle touches in the main view itself, rather than in the main view controller. If that is correct, the answer is no, you don't have to.
The way events work in Cocoa is that they propagate up through a chain of objects called the responder chain. The last/lowest object in the chain is given a chance to respond to the events first. In this case, that object is your "main view". If the object can not respond to the event, the event goes to the next object in the chain, what's called the object's next responder. This progresses up the chain until an object responds to the event.
The reason you don't have to worry about this is that a UIView's next responder is its view controller. This means that if you don't handle the event in your view, it propagates up to the view's controller (and, if you don't handle it there either, it continues up the responder chain). So, if you implement the -touchesBegan:withEvent:, -touchesMoved:withEvent, and the other event-based methods in your view controller and not in your view, you'll be fine.
For further reading on event handling in Cocoa, see this section of the iPhone Application Programming Guide.
Related
normally after a modal transition, the second viewController runs further "behind" the visible ViewController in the background.
Is there a possibility to completely unload the second ViewController ??
If don't want to use push, because I want an animation on the transition...
Several points:
You are worrying about something that is not a worry. View controllers are lightweight, simple objects. The only heavyweight object is the view, and it is in fact removed from the interface when another view controller's view is presented in its place.
The game does not "run in the background". If it does, you're doing it wrong. You should be detecting in viewDidDisappear: that your view is no longer in the interface and stopping all the activity. That's what these sorts of events are for.
If you're still bent on making certain the view controller itself is destroyed when the game is not showing, then use a different architecture. For example, present the game controller. When the game controller is dismissed, it will be released and destroyed.
Is it possible to access a NSWindowController's element from a child NSViewController?
Essentially I have a NSProgressIndicator that spins on the bottom corner of the NSWindow. This works because my WebView is in my NSWindowController instead of my NSViewController.
I want to break the logic apart now but I'm having trouble understanding how I'd access these elements from my View Controller.
Thanks!
You can't connect an outlet from one NIB to an object in another and the desire to do so indicates a problem with your design. If the view is so intimately connected to other things in the window, maybe it shouldn't be separated out into a different NIB.
A view should only go into a separate NIB when it makes sense as a self-contained unit. It should represent and manipulate its controller's representedObject and not much more. The controller might have a delegate that it informs about what's being done and asks to make customizing decisions.
Maybe you can continue to use a separate NIB if you adopt that sort of design. Perhaps the window will have a reference to some model object. It would configure the view controller to use that model object as its represented object. And perhaps the progress indicator would be bound to that same model object. Then, as the view manipulates its represented object, it would indirectly also affect the progress indicator.
Another option would be for the window controller to set itself as the delegate for the view controller and your view controller could invoke it at appropriate points to inform it of things going on in the view. Then the window controller could do whatever was appropriate to the progress indicator or other stuff in the window outside of the view. This hypothetical delegate is something you would have to add to the view controller class and you'd design its protocol.
I've got a UIView that I've subclassed to be the main view used throughout my app. In it, I have two subviews: banner and container. Banner is basically a place to put an ad or a disclaimer or whatever. Container is meant to act as the primary view, to which you can add, remove and whatever as if it were the only view.
Right now, I'm just overriding the methods of the parent view and sending the calls to the container view. I'm wondering if there is an easier way to do this, without having to write out stuff like this for every method:
- (void)addSubview:(UIView*)view {
[container addSubview:view];
}
Maybe something that lets you delegate all method calls to the view to a specific subview, rather than responding to the method calls itself.
Anyone know if this is possible?
I'm a little confused by the question.
The responder chain is present and passes ui events up through all visible views on screen, by hierarchy. It may be useful to read a little about the responder chain, because by design it passes events from the deepest view to the highest (root) in that order, which is the opposite of the direction you're seeking (if I'm reading this right).
If you need to forward events from a superview to a subview, to respect principles of encapsulation, you should define appropriate actions in your subview's subclass interface, and then then configure your superview to target the actions in that subview/class.
I have a series of UIView subclasses that are added as subviews. Each subview can be dragged and dropped. When they are dropped (touchesEnded), I need to run a method in the viewController to do some work. I currently have the touchEvents handled in each subview class. Should I be handling these touch events in the viewController or should I be passing a pointer to the parent viewController as a property of each class I have added as subviews?
UPDATE: Or is this a job for NotificationCenter?
UIViewController is a subclass of UIResponder, and instances are automatically inserted in the responder chain behind the views they control. As a result, you can implement the same event methods in subclasses of UIViewController as in subclasses of UIView, and they will 'just work'; that is, they'll be called automatically.
So if your view controller needs to respond to -touchesEnded:withEvent:, just implement the method directly in your UIViewController subclass. If the view also needs to do something in response to the event, you can always send it a message from within your -touchesEnded:withEvent: (or whatever) implementation.
You might try delegating your desired touch handling event from your uiview subclass to the uiviewcontroller using a delegate protocol. The view controller can set itself as delegate as it instantiates or adds each subview.
In MVC paradigm, if you want to handle a touch that's specific to a V view's internals (button appearance/location), then you might want to handle that touch in the V view, but if the touch effects some state outside the view (it's position in a bigger window, etc.) you might want to pass handling that touch up to the C controller to set state in the M model.
I wonder what is the proper way to get back some message from a child view.
I have a object that is edited in the child view. I wanna see in the TableView their modifications.
However, I don't know a clean way to do it (I don't like a singleton here).
Is possible get notified when the Child view dissapear and get some info on that?
You can use the UIViewController notifications viewWillDisappear: and viewDidDisappear: to be notified right before a certain UIView is about to disappear and right after it disappears respectively. Note that most of the various UIKit objects (including UITableView) are subclasses of UIView.
IMHO, the "correct" way would be to implement a custom protocol in the view's controller (probably navigation controller in your case) or the application delegate and have the child view communicate using it when it gets the viewWillDisappear and/or viewWillDisappear notifications (as mentioned in Adam's reply). Similarly, in the parent view you can refresh the necessary information in the viewWillAppear handler.
This way, the parent view is getting its data from the delegate and not directly from a specific child view, which maintains MVC in your design.
You could also issue a notification (using NSNotificationCenter) that the parent would be subscribed to listen for - that has the side benefit that other classes could be notified as well.
But if it's a pretty strict relationship where only the sub view and master table will care, you probably should set your table view controller as a delegate of the subview and have the subview call the delegate directly (a protocol as mentioned is a good idea for something like this).