my question relates to Interface Builder and an IKImageBrowserView not implementing bindings as I would expect.
I have a fairly long key path to get to an NSArrayController, the contents of which I want to display in the IKImageBrowserView.
This is the key path I am binding an NSTextField's Display Pattern binding to:
currentOrder.imagesArray.unvalidatedImages.arrangedObjects.#count of the AppDelegate.
This works fine and gives me the number of unvalidated items in the array of images belonging to the current order, which is what it is supposed to.
When I attempt to bind the following key path to the IKImageBrowserView's content: currentOrder.imagesArray.unvalidatedImages.arrangedObjects of the AppDelegate, Interface Builder gives no error but instead acts as if I hadn't entered anything. When I click back to the inspector, the bindings key path is blank again.
It does however log the following to the Console:
Ignoring exception related to working with bindings: NSUnknownKeyException, [<NSCustomObject> addObserver:<IKImageBrowserView ...> forKeyPath:#"currentOrder.imagesArray.unvalidatedImages.arrangedObjects" ...] was sent to an object that is not KVC-compliant for the "currentOrder" property.
My AppDelegate implements currentOrder as an #property retained and all sub-keys are also #properties. I can be sure that these properties are KVC-okay because the NSTextField above is able to read changes without a problem. Interestingly enough the IKImageBrowserView's selectionIndexes is able to bind to ...unvalidatedImages.selectionIndexes, it's only the content that can't.
I have implemented a workaround whereby I have placed an NSArrayController in my nib file and bound the Content Array to ...arrangedObjects then bound the IKImageBrowserView to the array controller but would be very happy to have a neater solution, or at least to know whether I am doing anything wrong.
Thank you!
Did you try implementing the methods of <IKImageBrowserDataSource> in your app delegate, and using the _dataSource connection instead of a binding? That works for me, and is how the Apple tutorial has you do it.
You basically only need to implement – numberOfItemsInImageBrowser: and – imageBrowser:itemAtIndex: to provide the data, which isn't too bad. The slightly trickier part is to implement an <IKImageBrowserItem> class to wrap your data, but even that doesn't require massive effort. The tutorial linked above should help a lot.
Related
I'm trying to set up a QCView inside a Cocoa project but seem to be going round in circles as much of the available documentation is depreciated. I've followed this:
http://kineme.net/forum/DevelopingCompositions/ProblemusingQCPatchController#comment-23250
And got some simple KVC bindings working. But can't work out how to access the published inputs on a code level.
I understand that you can use setValue: forKeyPath: but dont know how to access the Object controller that was created in the IB interface by dragging and dropping.
How can i find out what the active Object controller is called? Once I know what that ivar is, is it as simple as:
[NSObjectContoller setValue:(id) forKeyPath:(NSString)];
Or is there something more to this?
I've managed to work this out myself.
Create an IBOutlet from the Object Controller in your .h file. For Simplicity I'm doing this inside my AppDelegate.h
you can call setVlaue: forKeyPath: on your instance of the Object Controller.
For me this looks like:
[_theObjectController setValue:sender forKeyPath:#"selection.patch.Green.value"];
note that the key path is "selection.patch.Green.value" You need to add your controller key to the beginning of you Model Key Path.
I'm going through a simple Objective-C/Cocoa program to try and learn the language and am getting a little confused about how some things are linked from the code I write to the interface builder.
For example, I have a simple NSString:
#property (assign) NSString *letters;
And in my interface builder, I have a text field and I use the text field's bindings to connect it to letters.
However, the example also has this:
#property (assign) IBOutlet NSArrayController *wordsController;
In the view I have a table that continuously changes and shows different words and those words are stored in an NSMutableArray. I suppose I can understand that I just can't bind the array to the the table because there are some more complexities. So in the Interface Builder I create an Array Controller and bind it to the table. In the Array Controller's bindings, I bind the Array Controller to the array of words.
I understand that the last thing I have to do is also bind the Array Controller to my NSArrayController object as well. I don't understand why I do this through the main controller object by making a connection between this outlet and the wordsController. In the Array Controller's bindings section there's a greyed out option, Content Object, which says "An NSArrayController that the NSArrayController treats as its content." Why wouldn't I set the binding here? What is the significance of it being an outlet and why is it different than my NSString letters?
Thanks
You are confusing bindings and IBOutlets. This is not unreasonable -- it's a lot of Control-dragging of connections and it can be hard to keep clear what's going on. Let me try to explain:
Bindings are a way to let Cocoa handle the mechanics of keeping a model (some collection of data, even something as simple as a single NSString) and a view (an object which displays on the screen) in sync. When you "bind" your NSString to a text field's value, you are asking the framework to communicate changes to the string or the text field "behind the scenes"; your object which owns the string gets notified to change the string's value when the text field changes, and vice versa.*
A similar situation applies to your mutable array, array controller, and table view. You're essentially right about the complications: the mutable array and the table view don't know how to talk to each other; the array controller stands in between and facilitates: ("Okay, tableView wants to know what to put in row i. Array, give me your object at index i." :) In the past, you would've had to write that code manually, and it looked very similar every time you did so.
That's what the bindings do. They are a way to reduce boilerplate code. The IBOutlet to the array controller gives your object a way to send messages to the array controller, if necessary. One simple example of why you might need to do this is to allow a menu item to trigger a method in the array controller; a document object or another controller might handle the action from the menu item and call the appropriate message on the array controller. You can also ask the array controller for its arrangedObjects to get, for example, the sorted and filtered version of its content array.
* One side note here is that your NSString property should almost certainly use retain, not assign. The object that contains this variable should be responsible for its memory.
I am connecting an arraycontroller (myArraycontroller) in Interface Builder to an array (fileDictionariesArray) consisting of dictionaries. This works fine, but when I try to access and enumerate over the contents of the arraycontroller [myArrayController arrangedObjects] I get nil in content until I add the content programmatically to my arrayController like this:
[myArrayController addObjects:fileDictionariesArray];
After I have done that I can loop over all the contents. The problem is that the array (fileDictionariesArray) has been added two times. One time through IB binding and one time through addObjects. I just can't access the arrayContoller until I set the content programmatically. I can delete the content of the arrayController and then set it programmatically again like this:
[myArrayController setContent:nil];
[myArrayController addObjects:fileDictionariesArray];
Which gives the correct number of items in the arrayController, but it does not seem like the correct way to do this. I would appreciate it of anyone could give me a hint on how to access my arrayController through the arrangedObjects array without adding the content two times.
Thank you for your help. Cheers, Trond Kristiansen
Based on your post and the comments between you and Bavarious, I'm convinced he shouldn't have deleted his answer. He'd asked you where you were calling this code (from -awakeFromNib?). This is an essential question to answer.
If you call this from -awakeFromNib, the next question is "of what object in the nib? the owner? some other controller? what is the? a document?"
The thing is the array controller likely doesn't have time to observe the "changes" to the array before you call your code. That's why adding the content forcibly results in its being added twice (because after you're done, the array controller observes its content array and pulls in the content ... again ... at which point you've doubled the array's contents).
If you're doing immediate startup stuff, it might be best to operate directly on the array. There's nothing "wrong" or "dirty" about that, so long as you leave responsibility with the array controller after startup is complete.
It's hard to get any more specific because I'm just guessing at what you might be doing. Amend your question to include a more complete description of how/where your array controller fits into the architecture, what specifically you're doing to the array at startup, etc. Missing any of this information forces too many guesses.
Heys,
I am writing something in Xcode. I use Core Data for persistency and link the view and the model together with Cocoa Bindings; pretty much your ordinary Core Data application.
I have an array controller (NSArrayController) in my Xib. This has its managedObjectContext bound to the AppDelegate, as is convention, and tracks an entity. So far so good.
Now, the "Content Set" biding of this NSArrayController limits its content set (as you'd expect), by a keyPath from the selection in another NSArrayController (otherAc.selection.detailsOfMaster). This is the usual way to implement a Master-Detail relationship.
I want to variably change the key path at runtime, using other controls. This way, I sould return a content set that includes several other content sets, which is all advanced and beyond Interface Builder.
To achieve this, I think I should bind the Content Set to my AppDelegate instead. I have tried to do this, but don't know what methods to implement. If I just create the KVC methods (objectSet, setObjectSet), then I can provide a Content Set for the Array Controller in the contentSet method.
However, I don't think I'm binding this properly, because it doesn't "refresh". I'm new to binding; what do I need to implement to properly update the Content Set when other things, like the selection in the master NSArrayController, changes?
However, I don't think I'm binding this properly, because it doesn't "refresh".
This most often means you are assigning directly to the instance variable, not using KVC-compliant accessor methods nor posting KVO notifications.
The general solution is to create accessor methods for the property and then use them everywhere, including inside that class, except in its init and dealloc methods.
I'm really having trouble getting a Cocoa Table View cell to send action messages.
At the most basic level, in IB there is an action assigned for the NSTextViewCell object, and after editing and pressing Return nothing happens.
So I have an IBOutlet hooked up to the NSTextViewCell, and have been experimenting with NSActionCell messages to it. But the Table View seems to pretty much just ignore them.
I've also tried subclassing NSTextViewCell, but the methods I'm seeing all look like they want to pass values to the object from somewhere, not return a value from inside the object to configure its behavior.
I'm pretty new to programming and Cocoa -- can someone explain each thing that needs to be overridden and how and where to do it?
AFAIK, the cells in an NSTableView won't send action messages out to your application, they're sent to the NSTableView so it can update its data. NSTableView itself tries to be pretty clever and update your data directly, rather than just telling you something changed, so depending on what you're trying to do and what the data source for the table is, you have a few options.
If you're using an NSTableViewDataSource object to populate the table, it's simple; just implement tableView:setObjectValue:forTableColumn:row: and the NSTableView will call that every time something is edited.
If you're using Cocoa data binding (for example, using an NSArrayController to bind an array of objects to the table,) then as long as everything is wired up correctly, the data should just automagically get updated in the source objects when the table is edited. If you need to take special action, then you can do whatever you need to in the property setter of your data class.
I haven't tried it yet, but could work...
NSCell *cellYouWant = [tableView preparedCellAtColumn:tableView.clickedColumn row:tableView.clickedRow];