Unable to update NSTouchBar programmatically - swift

Question

I am currently developing a very simple Live Scores MAC OSX app for personal use where I show a bunch of labels (scores) on the touch bar. What I am trying to achieve in a few steps:
Fetch live soccer scores from a 3rd party API every 30 seconds
Parse the scores and make them into labels
Update the touch bar with new scores
[Please note here that this app will not be published anywhere, and is only for personal use. I am aware of the fact that Apple strictly advises against such type of content in the Touch Bar.]
Here is the code that I wrote following basic Touch Bar tutorial from RW (https://www.raywenderlich.com/883-how-to-use-nstouchbar-on-macos). Skeleton of my code is picked from the RW tutorial:
In WindowController (StoryBoard entry point), override makeTouchBar like this:
override func makeTouchBar() -> NSTouchBar? {
guard let viewController = contentViewController as? ViewController else {
return nil
}
return viewController.makeTouchBar()
}
In ViewController, which is also the Touch Bar Delegate, implement the makeTouchBar fn:
override func makeTouchBar() -> NSTouchBar? {
let touchBar = NSTouchBar()
touchBar.delegate = self
touchBar.customizationIdentifier = .scoresBar
touchBar.defaultItemIdentifiers = [.match1, .flexibleSpace, .match2, ... , .match10]
return touchBar
}
NSTouchBarDelegate in ViewController. scores is where I store my fetched scores (See 5). I return nil for views if scores aren't fetched yet:
extension ViewController: NSTouchBarDelegate {
func touchBar(_ touchBar: NSTouchBar, makeItemForIdentifier identifier: NSTouchBarItem.Identifier) -> NSTouchBarItem? {
if (<scores not fetched yet>) {
return nil
}
// matchNum is the match number for which I am showing scores for
let customViewItem = NSCustomTouchBarItem(identifier: identifier)
customViewItem.view = NSTextField(labelWithString: self.scores[matchNum ?? 0])
return customViewItem
}
}
To fetch scores periodically I am running a scheduled task Timer in viewDidLoad() of my viewcontroller like this:
_ = Timer.scheduledTimer(timeInterval: 30.0, target: self, selector: #selector(ViewController.fetchScores), userInfo: nil, repeats: true)
And finally, this is my fetchScores function that also makes a call to update the Touch Bar:
#objc func fetchScores() {
let url = "<scores api end point>"
Alamofire.request(url).responseJSON { response in
if let json = response.result.value {
// update self.scores here and fill it with latest scores
if #available(OSX 10.12.2, *) {
//self.touchBar = nil
self.touchBar = self.makeTouchBar() // This is where I am calling makeTouchBar again to update Touch Bar content dynamically
}
}
}
My understanding from the code above is that once I make a call to makeTouchBar in fetchScores and assign it to my viewcontroller's touchBar property, it should ideally call touchBar(:makeItemForIdentifier) delegate function to update the Touch Bar view (SO thread on this). But in my case, touchBar(:makeItemForIdentifier) is never called. The only time touchBar(:makeItemForIdentifier) is called is the first time, when makeTouchBar is called from my WindowController (See point 1 above). And since scores have not been retrieved yet, my touch bar remains empty.