Ok. this one's a challenge.
I have a tableview within a navigation controller.
I push it from the root, where I have an add action that allows me to add a new record. That works fine.
Now what I've tried to do is add this tableview to a tab bar view (without a tab bar controller cuz that won't work) but within the same navigation controller.
So what I want to do is this: Root > TabBarView (loads Tableview) > add new record.
The problem lies in the managed object context, I get the whole "can't find entity error" but I have no idea how to fix it.
I've managed to get the AddRecord modal view controller to show up from the tabBarView, but it presents itself without a navigationbar, whereas if I try to add a record in the solitary tableView (outside of the tabbar) its no problem.
I'm now calling my methods from the TabBarView's navigationBarbuttons, routing through to the tableviews methods.
I know my methods have to be called from the tabBarView instead of the actual tableview now, and they do fire, but I don't know how to manage the MOC when its in a tabView.
Oh, and this is based on coredata recipes and books, so when the add record method is fired, it creates a new MOC to create it, then reintegrates back in the main MOC when you're done.
Any ideas?
It sounds like you have a couple of problems.
"Can't find entity" error -- this depends on which Managed Object Context you're using. If you created a separate MOC to manage the object you're editing (which is a good idea, by the way), make sure you assign it a Persistent Store Coordinator. This is how an MOC discovers what objects are available. If you're using the MOC created in the App Delegate, make sure you're spelling the name of the entity correctly.
No Navigation Bar in sheet -- When you push a view controller onto a navigation controller, its navigationItem is used to populate the navigation bar. When you present a view controller as a sheet, only the view controller is displayed. It is not embedded in a navigation controller. In order to get the navigation item to display, you'll need to create a new navigation controller with your view controller as the root, and then present the navigation controller's view.
As far as the main MOC goes, views and controllers should be irrelevant. Obtain a reference to the MOC in whatever controller you are using and operate with that MOC. If your application delegate creates the main MOC, make it a property of that delegate and access that from your view or tab controller.
I don't quite follow what navigation problem you're having, but if there's no navigation bar when you need one, I suspect you need to create and add a UINavigationController somewhere that you're adding a UIViewController subclass. Make the subclass the root of the new UINavigationController and put the controller into the tab or whatever.
Your managed object context (MOC) should not be dependent on navigation or views. It's part of the model. (Although as you know, a 2nd MOC for a cancelable edit view would be dependent on navigation to the extent that you create it for use by the editor.)
Related
I'm creating an app using the iPhone Utility App framework, and I'm trying to use a navigation controller on the flipside view, as there will be a lot of drilldown options on this view. When I'm done with this view, I call the following code:
- (IBAction)done:(id)sender
{
[self dismissModalViewControllerAnimated:YES];
}
When I dismiss this view, I want to be able to go back to the place in the navigation I was currently at when I reopen this view again. However, when I dismiss this view using this method, the vc gets deallocated, therefore the menu starts back at the beginning when I try to go back to the menu.
Thoughts?
You'll need to retain a reference to the object (I'm calling it the options controller). I would say the easiest way is to create an iVar in the presenting view controller that references the options controller. Then, when you go to present the options controller again, just present the referenced options controller rather than creating a new controller. If different view controller objects can present the options controller, you'll need to either pass that reference around, or store it in some object that all the other view controllers have access to.
Hmm not much code so maybe I'm misunderstanding your setup, but...
You could use the AppDelegate to store (as a property) your current position (index) in the views collection of the Navigation controller, and then write a method that pushes to that (stored) position when you re-visit it later.
Might be an easier way to do it though..
So what you want is to flip from a view to another view? If you want to keep the navigation bar status between flipping, I recommend you use only one view controller to control this 2 views. you can use + transitionFromView:toView:duration:options:completion: of UIView to flip views.
In an iPad application I have a tab Controller containing several view controllers. One of these view Controller (call it MainViewController) needs 2 table views side by side.
So I wrote 2 UITableViewController subclasses and from MainViewController, I alloc/init both subclasses of UITableViewController, and add the tableview from each to the MainViewController's view.
This means that UITableViewController subclasses's views are subviews of MainViewController's view.
This answer: https://stackoverflow.com/a/7684648/191463 says that doing that is incorrect and it seems Apple are starting to cut down on it.
I really do not want to have to put all the code from both UITableViewControllers in MainViewController, as it will make it much harder to read and in future could create duplicate code, if I want to use one of the tableview elsewhere in the app by itself.
Is this actually a problem, if it is how do I do it properly?
Apple isn't cutting down on it. This is the only way to create custom container view controllers prior to iOS 5. Apple actually listened to the developers and made it easier to do this sort of thing in iOS 5 with child and parent view controller methods, not to mention they made it so it worked hierarchically.
In most cases, this wouldn't actually be a problem in terms of applications crashing or performance or anything. It can be a problem in some cases, because let's say you have a child view controller. You add the view controller's view to your root view controller. Prior to iOS 5, child view controllers were things like navigation controller view controllers, tab bar controller view controllers, and modal view controllers. What happens when you have a button that calls [self.parentViewController dismissModalViewControllerAnimated:YES];? Technically, the view controller isn't being presented as a modal view controller, you added the view to the root view controller view.
In iOS5, you're able to add child view controllers to view controllers and are able to transition from one child view controller to another.
Now even if your view controller doesn't have a different parent, adding a "root" view controller to another root view controller isn't the best way to do it (especially since you don't get access to the parent view controller unless you explicitly create a parentViewController pointer in the child view controller). So in the end, Apple just made it easier and more decoupled.
It is OK to do it so long you take the responsibility of managing the viewController life cycle events
initWithNibName...
loadView:
viewDidLoad:...
.
.
viewDidUnload..
dealloc
memoryWarnings
orientation changes
So if you create a custom "container view controller" it becomes your responsibility to call all these methods on child viewControllers at the appropriate time. Think of it as "If you were to implement UITabBarController" what all will you have to manage regarding the children ??"
It quickly gets complex. Adding another viewController's view as subview is childs play.
iOS 5 does some of this stuff for you by specifying parent child relationship, however I still haven't seen any sample code anywhere yet to point to.
I'd say it is not incorrect or wrong to create view controller containers, especially when Apple engineers do that themselves. UITabBarController, UINavigationController or UISplitViewController - they are all view controller containers. More over many great apps with unique UX do that more common than you think. However the real issue is that it's quite hard to do it the right way, so e.g. view lifecycle, memory management and rotation handling is done properly along the hierarchy of views. Fortunately Apple guys did a decent job and iOS5 introduced lots of functionalities regarding controller containers:
UIViewController class reference
View Controller Programming Guide for iOS
If you're interested how above problems had to be addressed before iOS5, read these two very good blog posts:
Writing high-quality view controller containers
Using view controllers wisely
I have a navigation controller which I push a new tableviewcontroller for each received question to be asked to the user, so in stack it builds up to 30 controllers if there has been 30 question is asked.
The difficulty is that in some of the tableviewcontrollers I want to get the input from user by using another navigation controller inside that tableview: for example in the tableview(which is one the many views in the stack) there may be uitablecell with an arrow on the right saying choose the books you want to order, and when he clicks arrow a new tableview will slide in which includes the books to be choosen multiply with a checkmark, and then he will choose and back to main tableview and continue the main navigation there.
How can implement a new navcontroller inside the main navigation controller? or any better ideas?
EDIT: That can be an idea to push the detail view to the same controller, but then they will get popped immdidatly when user "backs" but I want to show the books (which are chosen in detail view) the main table, and when user clicks again to that cell, detailview will come with previous selected books. is this a good approach
Putting an UINavigationController inside a UINavigationController is a bad idea. What you seem to really want is persistence of state data after popping some of the view controllers off your navigation controller's stack.
I would put that state information into a persistent object. If it's a tiny amount of state data I may add that data to an existing object that I know is persistent, such as the app delegate or the root view controller. I would save a more complicated set of persistent data to a custom object. This object would be retained by the root view controller, and a reference would be given to each successive view controller. This object would have the data that may have been collected by a controller that was popped off the navigation stack and therefore no longer exists.
I don't really get why you dont just push the detailview of the uitableviewcontrollers to the main UINavigationController..
Could you explain that a little bit more detailed?
I have no rights to comment your question, so I am afraid I have to post this as an answer.
MfG,
SideSwipe
I'm trying to display a controller loaded from a NIB in my navigation controller (iOS 4/Xcode 4), but it is not working. Interface Builder doesn't allow me to choose any of my nibs; when I try to manually type one I get this error:
warning: Unsupported Configuration: Navigation Controller NIB Name set to MyViewController.nib (This view controller is not intended to have its view set in this manner)
What's this all about? One thing to make note of: I manually added the Navigation Controller after creating a view-based project. I decided that I should use one after I had already created the project, instead of choosing Nav-based from the beginning. Perhaps I forgot a setting?
I think you're trying to set the NIB of the navigation controller itself.
This is not what you want to do: you instead want to set the nib of the root view controller of your navigation controller. To do this, you should expand the navigation controller via the navigation panel (the left hand panel with a list of all the objects in your current NIB).
Selected 'Root View Controller', and then set its NIB and class as appropriate.
The reason you're getting an error right now is you're actually trying to set the navigation controller's NIB, which XCode is quite rightly not letting you do.
I have a table view that contains a list of Project objects. When an item is selected it brings up a detail view. Pretty standard. What is the best way to implement "add" functionality (popup a modal view controller to input new values and save the item)?
Currently I have view controllers for my root view, detail view, and add view. Essentially the detail view and add view are exactly the same except for a save & cancel button in the add view. Is it possible to reuse the detail view in the add view?
Finally, what is the best way to display the list of project properties in a grouped table view separated into sections?
Thank you for your responses.
Most likely, you are already passing your detail view controller a managed object that it is supposed to display when in detail view mode. When the user decides to add a new project, just create a blank object, pass it to the detail controller and display it. (You might want to insert this blank object into another "empty" managed object context in case the user cancels the add process to avoid having to clean up your main managed object context in that case.)
The detail view controller would also need a flag that tells it whether it is in edit or add mode so it can adjust its controls (and possibly delegate messages it sends to its owner) accordingly. You would set the flag to the appropriate value before you display the controller.
It sounds like you're looking for a UINavigationController. The UINavigationController lets you push new view controllers on top of existing ones. It gives you a navigation bar at the top that will allow the user to go back to the root controller. I think it's the kind of controller Apple uses it in the default email application, to give you an example.
Concerning organization: you design your root view controller and a detail/add view controller. In your app delegate, you attach a UINavigationController to the window and you set its root controller to the main controller you want to display. That root controller can then push the add/detail controller onto the stack (and when it does so, it can tell the add/detail controller which types of button to display.)
I can't answer your grouped properties question, but it sounds like a separate question anyway.