I have an NSTableView, and I've used Interface Builder to bind its Content to an instance of an NSArrayController subclass. I have Controller Key set to arrangedObjects.
So far so good: If I just load an array of strings into my NSArrayController (using addObjects) and leave the Model Key Path blank, those strings show up in the table.
However, if I add an array of dictionaries to my NSArrayController, such that each dictionary has a name property, and I set Model Key Path to name, the table just shows a stringified version of the entire arrangedObjects array n times, where n is the length of the array. Indeed, this happens no matter whether Model Key Path is set to name, foo, or blank.
I just want the NSTableView to display the name property of each dictionary in arrangedObjects. What am I doing wrong?
Figured it out: In addition to binding the aforementioned NSTableView's Content (which turned out to be irrelevant), I'd bound the corresponding NSTableColumn's Value to have the controller arrangedObjects, with no Model Key Path. Setting that to name made everything work fine.
Related
Hey I am new to mac development and I want to use bindings (xcode 5.1.1).
I want to set the Title of a radio button dynamically by an entry of an array controller. I am looking for something like a syntax description how I can perform it.
e.g. something like value1 WHERE value2="bla"
If I trying to search at google I always find solutions which did it programmatically.
Is there anywhere some examples which show me the syntax I can use in this field?
The picture below should you show what I mean.
Answering the question as clarified in the comments…
First, bindings is not always the right technology. It can simplify some things, but it can't do everything and even for some of the things that it can do, it doesn't necessarily make them simpler.
Radio buttons are often organized in an NSMatrix. In that case, you can bind the matrix bindings to track the selection. There are three content-related bindings for a matrix, which can be kind of confusing. The "content" binding is the base. In some cases, it's sufficient. However, if there's a distinction between the object being bound and the value that should be shown by the cells of the matrix, then you can bind the "contentValues" binding to be a subpath of the content binding. That is, it needs to be the same as the content binding with possibly additional elements added to the end of the model key path.
Furthermore, if you want the selected object to be distinct from the content object, you can bind "contentObjects" to a subpath of the content binding.
For example, there may be an array controller whose content is a bunch of Person objects. The matrix content binding might be bound to that array controller's arrangedObjects. If you leave it like that, the cells of the matrix will be populated from the description of each Person object. However, you could bind the matrix's contentValues to the array controller, arrangedObjects, model key path fullName. Then, the matrix cells will be populated with the full name of each Person object.
If you then bind the matrix's selectedObject binding to a property on your window controller, that property will be set to the selected Person object each time the matrix selection changes. If you would prefer, you could bind the matrix's contentObjects binding to the array controller, arrangedObjects, model key path uniqueID. In that case, the window controller property would not be set to the selected Person object itself, but to its uniqueID property.
Alternatively, you could bind the matrix's selectedIndex binding to a controller property. If you use the window controller, then that just directly sets a property on the window controller to indicate the index of the matrix's selection. Or you could bind it to the array controller's selectedIndex property, in which case the selection is "stored" in the array controller.
You need a keypath that takes no parameter as described in the key-value coding (KVC) reference.
By binding to an array controller's selection, if the selection collection is one object with a property or method "value1," then the binding runtime is calling the method valueForKeyPath:#"value1".
The NSObject protocol has performSelector:withObject, but there is nothing like valueForKeyPath:withObject in the KVC protocol or the NSKeyValueBindingCreation protocol
That said, registering dependent keypaths can provide some equivalent behavior...
+ (NSSet*) keyPathsForValuesAffectingValue1
{
return [NSSet setWithObjects:#"value2",nil];
}
... and that would ensure that any time value2 changes, the binding to value1 is re-evaluated.
Is there a simple way to bind a NSMutableArray made up of Strings to a Single column NSTableView without creating any new classes?
Make an NSArrayController in interface builder. Bind its Content Array to your mutable array, like so:
Then bind your table column to that array controller, like so:
(Note the self in the model key path field. That's what makes it work with an array of strings.)
Assuming you're using a view-based NSTableView, you must bind the entire table view (not the column) to the array controller's arrangedObjects. Then, bind the text field's value to the containing cell view's objectValue property.
This is documented here.
For cell-based NSTableViews, Amy Worrall's answer is the correct approach.
I'm exploring bindings right now, and have an NSPopUpButton -
It presents me a number of options for bindings under Value Selection - Content, Content Objects, Content Values, and then Selected Object, Selected Value, and Selected Tag. Could someone please explain the difference between these?
Those are explained in the Cocoa Bindings Reference for NSPopUpButton, although that reference is not quite clear.
Content is an array controller that provides elements to the popup button. The array controller should be bound to an array. In order to determine how each element in the array is shown in the popup button, -description is sent to each object in the array.
You may customise this in two ways:
If you want the Selected Object binding to provide an object distinct from the array elements managed by the array controller to which Content was bound, you can bind Content Objects to another array controller. It could also be the same array controller but with a different key path;
If you want the popup button options to be something different than the description of each element in the array managed by the array controller to which Content was bound, you can bind Content Values to another array controller that manages an array whose elements contain the popup options. It could also be the same array controller but with a different key path.
A simple example: suppose you have the following class:
#interface Customer : NSObject
#property (copy) NSString *name;
#property (copy) NSString *phoneNumber;
#end
and you haven’t overridden the -description method. In this case, -descriptionis useless and the name property would be a good choice for the popup options. You’d bind:
Content to an array controller that manages an array of Customer instances, controller key arrangedObjects;
Content Values to the same array controller, controller key arrangedObjects, model keypath name.
You can then bind Selected Object to something else, for example a property in your application delegate or window controller. Cocoa bindings would then assign the selected Customer instance to that property.
Now suppose you are not interested in the whole Customer object that’s been selected, but only its phone number. In this case, you can bind Content Objects to the same array controller, controller key arrangedObjects, model keypath phoneNumber. When a popup option is selected, Cocoa bindings will set phoneNumber instead of an entire Customer instance. In summary: if you don’t bind Content Objects, Selected Object represents the original object in the array. If you bind Content Objects, then Selected Object can be something different.
You’d bind Selected Value if you were not interested in the original objects (or the content objects), but the actual strings shown in the popup options according to the Content Values bindings.
Quick recipe for providing data to the popup button:
Bind Content if you have objects (not only strings) that represent the popup options;
Bind Content Values if the options that are shown to the user cannot be obtained via Content by sending -description to the array elements;
Bind Content Objects if you want Selected Object to return something different from the array elements from Content.
Quick recipe for obtaining the current selection in a popup button:
Bind Selected Object if you want to know the full object (either from Content or Content Objects) representing the current popup selection;
Bind Selected Value if you only want the string that’s currently selected in the popup.
And lastly, you’d use Selected Tag if the popup options are actually taken from a menu whose items have a tag set.
#Object refers to any KVC-compliant object. #ObjectValue refers to the key path used to get the value from that object.
So, for your pop-up binding, ContentObjects would be bound to, say, an NSArrayController's arrangedObjects. Say this refers to an array of dictionaries or managed objects. You can't meaningfully present a dictionary in a pop-up (you get the start of the description output, e.g <NSCFDictionary... or similar), so this is where the contentValues binding comes in. This would be something like your NSArrayController's arrangedObjects.name, where name is a key from your dictionary or managed object.
I hope this helps, I struggled with the same concept myself when I started with bindings.
Thanks for the help.
Core Data project. I'm importing text from a text file and I want to display it in an NSTextView whose value binding I have bound to the arrayController's selection with model key path text. The array controller contains instances of my entity, which has a string attribute named text. I want to update the arrayController for the key value bound to the textView so it can be saved. No errors when building, but not working. How do I do this?
id newObject = [arrayController newObject];
[arrayController addObject:newObject forKey:#"text"];
[newObject release];
[arrayController addObject:newObject forKey:#"text"];
This is “not working” because an NSArrayController doesn't respond to such a message. An array controller controls an array, not a key-value mapping; it does not have keys you can add objects for.
That, in turn, is because “array” in Cocoa means an ordered consecutive list, not an associative array. Cocoa calls a key-value mapping/associative array a “dictionary”.
The model key path is exactly that: The key path into the model of the property you want to bind the text view to. You seem to already know this; I assume you entered text here because it's what you named the attribute in your model. Your binding is correct.
But this also means that “text” has nothing to do with the array controller. It is a property of the model entities, not the controller. You need to set that property of the model object—in this case, newObject—not in the controller.
Is it possible to set a default selection on an NSPopupButton? I have one that allows the user to select the type of server they want to set up, but since an NSPopupButton always shows the first item, they may ignore it if that's the type they want. However, even though that item is being displayed, calling -selectedItem returns (null). Everything works fine if the user picks an item from the menu first.
The Button's content and contentValues are bound to the same Array Controller, which in turn is bound to the keys property of an NSDictionary. I've tried binding the selectedIndex to a variable in the controller and updating that in code, but it has no effect. (I may just be binding it wrong...) How can I select the first item by default?
Thanks in advance!
SphereCat1
When using Bindings, you don't need to and shouldn't get any model info—neither the model itself nor selection state—from the views directly. Talk to the controller that owns the model and the selected indexes.
Note that “index” doesn't have any meaning for an NSDictionary, and keys is not a property of an NSDictionary. (Indeed, I would not be surprised if you were to get an exception because your dictionary does not have an object for the key “keys” in it.) It is a method, and not the accessor kind, so while you can ask the dictionary for the value of that method using Key-Value Coding, you should not.
What you should do is make model objects representing the server types, and hold an array of those, and bind the array controller's content to the property whose value is that array. Bind the pop-up button's contentValues to a name property of your model objects, which should hold the localized name of each server type.