TouchBarItemsIdentifier

ViewController.swift

// ViewController.swift
fileprivate extension NSTouchBarCustomizationIdentifier {
    static let counterTouchBar = NSTouchBarCustomizationIdentifier("com.n3tr.countertouchbar.counter")
}

fileprivate extension NSTouchBarItemIdentifier {
    static let increase = NSTouchBarItemIdentifier("com.n3tr.countertouchbar.increase")
    static let decrease = NSTouchBarItemIdentifier("com.n3tr.countertouchbar.decrease")
    static let counter = NSTouchBarItemIdentifier("com.n3tr.countertouchbar.counter")
}

class ViewController: NSViewController {
    // ...   
}