Why is my array empty when updating the view? (Swift)

Question

Whilst debugging I can see that the fixtureList in the controller returns 6 values. However, when the code jumps into the fixtureView.update(...) within the View, the fixtureList value is 0.

I'm sure it's something to do with creating the same variable in both controller and view, but can't figure it out!

What would be the best way to resolve this issue? Esentially I want the 6 values to be received by the View so that the user interface can be populated.

Controller

var fixtureList = [Fixture]()

func updateScores() {
    liveScoreApi.fetchFixtures() { (
        isOK, fixture) in
        if isOK == true {
                for fixture in (fixture?.fixtures)! {
                    self.fixtureList.append(fixture)
                 }
            self.fixtureView.update(/*dump*/(self.fixtureList))
            }
        else {
            NSLog("error fetching!")
        }
    }
}

View

class FixtureView: NSView {

@IBOutlet weak var homeNameTextField: NSTextField!
@IBOutlet weak var timeTextField: NSTextField!
@IBOutlet weak var awayNameTextField: NSTextField!

let fixtureList = [Fixture]()

func update(_ fixture: [Fixture]) {
    // do UI updates on the main thread
    DispatchQueue.main.async {
        for fixture in self.fixtureList {
                self.homeNameTextField.stringValue = fixture.homeName
                self.timeTextField.stringValue = fixture.time
                self.awayNameTextField.stringValue = fixture.awayName
                print("added \(fixture.homeName)")
            }
        }
    }
}

If you break on DispatchQueue, is your fixture parameter empty as well? Shouldn't you be iterating over that value? — Dan Beaulieu
– Dan Beaulieu, Commented Jun 4, 2018 at 18:10
Added break to DispatchQueue - fixture has 6 values. You might be right actually, how would I implement this? — baze
– baze, Commented Jun 4, 2018 at 18:25

Dan Beaulieu · Accepted Answer · 2018-07-27 02:08:54Z

1

Your update method should look like this:

//let fixtureList = [Fixture]() // you don't need this

func update(_ fixtureList: [Fixture]) {
    // do UI updates on the main thread
    DispatchQueue.main.async {
        // (though you probably don't want this ultimately)
        for fixture in fixtureList {
            self.homeNameTextField.stringValue = fixture.homeName
            self.timeTextField.stringValue = fixture.time
            self.awayNameTextField.stringValue = fixture.awayName
            print("added \(fixture.homeName)") 
        }
    }
}

The problem is that you are newing up an array of Fixture objects at the class level. Then, inside your update method, you are attempting to iterate over the new array rather than your passed in array.

Just eliminate the unnecessary array at the class level.
change the name of your parameter to fixtureList
remove self. from fixtureList your for in loop

edited Jul 27, 2018 at 2:08

answered Jun 4, 2018 at 18:27

Dan Beaulieu

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9 Comments

baze Over a year ago

Ah yes, that's perfect. Cheers! Makes sense. Probably a separate question, but any idea why only the last value in fixtureList is displayed on the UI?

Dan Beaulieu Over a year ago

Oh yeah, for sure. So think about what this for loop is doing. Each time it iterates its setting your three labels to the current iteration's value over writing the previous value. So, naturally, whatever the last value that was iterated over, will be the only thing that you see. Let me know if that makes sense @baze

baze Over a year ago

Of course, yeah that's it. I'll have a go at resolving this. Although if I remove the loop, to access the homeName for example I need to specify an index: self.homeNameTextField.stringValue = fixtureList[1].homeName. But I want to update all homeNames, not just [1]

Dan Beaulieu Over a year ago

@baze Should you be using a table view for this situation? If you feel like you are on the correct path, you can get the iterator like this : stackoverflow.com/a/24028458/1664443

baze Over a year ago

Potentially yes, it sounds like that may be better suited. Although I'm not sure! I'm creating a menu bar app which currently has those 3 labels on. Thanks, I'll take a look

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