How do I bind all corresponding elements of several arrays?
Wendt's book Cocoa shows an example binding a property, a slider, and a textfield in IB. Change any one and the other two track its value. It's very simple. Wendt strongly makes the point that controllers are not necessary in simple cases.
I would like to extend this to binding an array of properties, an array of sliders, and an array of textfields. Change the 3rd slider, for example, and the 3rd property and 3rd textfield should change accordingly.
But would an NSArrayController be of any benefit in this case? I plead ignorance because all the examples I've found show NSArrayController used only with NSTable.
Related
I'm not sure if this is a feature or a bug, but when I have two collection views on a view controller using the same instance of UICollectionViewFlowLayout, an interesting thing happens. Note that I'm not using Interface Builder / XIBs for any of this; I'm laying everything out in code.
The first UICollectionView has twelve cells in it, but the second one has 20. When I reload both collection views, both act as if their contentSize property has 20 cells in it. This means that when I scroll to the right of the first UICollectionView and get past the first (and only) 12 cells, my app crashes (because I'm pulling data from an array that only has 12 cells' worth of data).
To get around this for now, I'm instantiating two identical UICollectionViewFlowLayout objects and assigning each to its own collection view. Is this normal behavior?
I'm only getting started writing code with UICollectionViews, so forgive my ignorance if I'm exuding any!
Don't do this. A collection view and a layout object should be a 1:1 relationship. The layout object has a property, collectionView, which obviously can only hold a reference to one collection view.
When the collection view then asks the layout for its size and so forth, the layout object is going to base everything on the second collection view you assigned the layout to, since this will be held in the collectionView property.
I couldn't find an explicit statement in the docs not to share a layout object between collection views, but the property discussed above should make it clear that this is not an intended use.
I'm trying to develop a NSPopUpButton that will serve as a filter to some datasource, let's say a NSArrayController that fills a table.
I can bind the NSArrayController from the menu to the selection keypath so the data is properly filtered, no problem with that.
Tricky part is, I want the content of this NSPopUpButton to rely on an NSArrayController using bindings, but I'd like to add a "Show All" menu item, or at least some item that doesn't come from the Core Data and performs some special action other than filtering the table using bindings and core data.
I'm trying to perform something like the NSPopUpButton used by finder in the filter bar, the last item of the menu performs a special action, while the others just filter the result.
I understand that the approach is to forget about bindings and do it everything programmatically, because I believe there's no way to mess up with the NSArrayController and bindings to add this custom menu item that doesn't rely on core data, but since I haven't found anything on the Apple Docs and here, I'd like to share my thoughts... any ideas?
sounds to me like you're looking for the NSContentPlacementTagBindingOption.
you edit the NSMenu that's attached to the NSPopupButton as follows
you then edit the settings on the NSMenuItem you want to have replaced with your array controller contents so that it has a meaningful tag associated with it
you then specify that tag as the content placement tag value on the NSPopupButton's bindings for the content/content* bindings.
I've got an application here that needs to read in a bunch of data from an external file and display it as a NSPopUpButton in a Cocoa user interface. The catch here is that the data that is being read in needs to have a flag that states if it is considered "hidden" or not.
If the data is hidden, it needs to be added to the NSPopUpButton as an NSMenuItem, but the hidden flag needs to be set to YES so it does not normally appear in the NSPopUpButton menu. If the user holds down a "magic key" on their keyboard (usually ALT, in this case) then those hidden objects need to be unhidden. If the user lets go of the ALT key, then they need to be automatically re-hidden, except for the one that may have been selected -- which would become hidden if another NSMenuItem were chosen.
I'm kind of having a heck of a time figuring this out, actually.
I was wondering if there is a straight forward way of doing this using NSArrayController and an NSPopUpButton, but thus far I have not been able to find anything resembling a solution -- not when it comes to managing the hidden property of the NSMenuItem objects.
Does anyone know how this can be achieved using Cocoa Bindings?
You can wire the popup to an array controller and alter the filter predicate. From an MVC design standpoint, you wouldn't use an attribute like "hidden", which is a view characteristic, but maybe "advanced". Normally, set a filter predicate on your array controller to "advanced = no". Then when the user holds your preferred modifier, remove the predicate. The popup will update automatically. The array controller should be bound to an array property on another object (in your data model). The popup should be bound to arrangedObjects on the array controller.
Does anyone have any info on this? I'm new to cocoa, all tutorials seem to be for iPhone which uses a different view controller. Anyone willing to provide a step by step for adding labels to a custom cell? (I'm pulling from Core Data)
EDIT: It's important to note I'm using Core Data here. Many tutorials use arrays.. I don't understand why you would use that??
I'll award an answer quickly!
Zach
I'm not sure if this is going to help you, but your problem seems unrelated to your use of CoreData.
If I've understood your problem correctly, here are some steps:
Populate your NSTableView
Using CoreData, what you can do is put an NSArrayController object in your XIB document, set its mode to Entity and choose the Entity you want to display in your TableView (all of this from the first tab of the inspector on your array controller object).
Then, bind your NSTableView Content to the arrangedObjects of the array controller. You might also bind the selectionIndexes and use some sort descriptors on the array controller to order your data, as CoreData will give you a set rather than an array.
Click on your table view as many times as necessary as to select the table column in which you want your custom cell to appear, and set its Value binding to arrangedObjects too.
Set your custom cell
Finally, click on the cell of this table column and in the "Identity" of the inspector, change the class name of the cell to the class name of your custom cell.
I'll let you read the appropriate documentation to implement your custom cell according to what you want to achieve.
With the different bindings I've described, the objectValue of your cell should be the object from your array controller at the same index of the row your cell will appear on.
Please note that I've not tested again all of these steps but answered from memory... there might be details I've missed but you should have the main steps here.
I need to create an NSMatrix with NSImageCells bound to an array controller. So the content of the NSMatrix is bound to an NSArray (so there are as many NSImageCells in the matrix as there are objects in the array), then the image path of the NSImageCells are bound to a key called "iconPath" in the Array Controller.
And then when an image cell is clicked in the matrix, I need it to perform an action. I know how to use bindings, and I have a concept like this working in an NSTableView, but I have never used NSMatrix before, so are there any good resources or sample code that would help me get started with this?
Thanks
If you want them to send actions when you click on them, then you probably want NSButtonCell instead of NSImageCell. A button cell can still contain an image.