CODEWITHSUNDEEP
cocoacocoa-bindings
MatterGoal
MatterGoal

Reputation: 16430

Binding and NSPopUpButton: changing the value of the current key doesn't change the selection

I've a really simple UI with a single NSPopUpButton. Its selectedIndex is bound to an int value ViewController.self.my_selection. As soon as I change the selection from the UI (i.e. a select the third item of the NSPopUpButton) I see that my_selection value changes. So far so good, what I'm trying to obtain is the opposed direction though. I want to change the my_selection value programmatically and see the NSPopUpButton selecting the item a the index that I've defined in my_selection. I erroneously supposed that behaviour was the default behaviour for bindings...

This is what I'm obtaining now: 

NSPoPUpButton ---> select item at index 2 ----> my_selection becomes equal to 2

This is what I want to achieve (keeping also the previous behaviour)

my_selection ---> set value to 3----> NSPoPUpButton selected index = 3

Upvotes: 0

Views: 904

Answers (1)

Paul Patterson
Paul Patterson

Reputation: 6918

Without a bit more info (see my comment) it's hard to see exactly what you're doing wrong. Here's how I got it working: First, create a simple class...

// Create a simple class
class Beatle: NSObject {
    convenience init(name: String) {
        self.init()
        self.name = name
    }
    dynamic var name: String?
}

Then, in the AppDelegate I created a four-item array called beatles:

dynamic var beatles: [Beatle]?

func applicationDidFinishLaunching(aNotification: NSNotification) {

    beatles = [Beatle(name: "John"), 
        Beatle(name: "Paul"), 
        Beatle(name: "Ringo"), 
        Beatle(name: "George")]
}

In Interface Builder I set things up so that this array provides the pop-up with its content:

enter image description here

This class also has a selectedIndex property that is bound to the pop-up button's selectedIndex binding - this property provides read-write access to the pop-up button's selection:

// Set the pop-up selection by changing the value of this variable.
// (Make sure you mark it as dynamic.)
dynamic var selectedIndex: Int = 0

Upvotes: 2

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