NSProgressIndicator loading extension

NSProgressIndicator+Loading.swift

#if os(macOS)

import Cocoa

/// Add loading property for NSProgressIndicator
extension NSProgressIndicator {
    struct Holder {
        static var _loading: Bool = false
        static var _hideWhenAnimationStop: Bool = false
    }
    
    var hideWhenAnimationStop: Bool {
        get {
            return Holder._hideWhenAnimationStop
        }
        set {
            Holder._hideWhenAnimationStop = newValue
        }
    }
    
    var loading: Bool {
        get {
            return Holder._loading
        }
        set {
            isHidden = false
            
            Holder._loading = newValue
            if newValue {
                startAnimation(nil)
            } else {
                stopAnimation(nil)
                if hideWhenAnimationStop { isHidden = true }
            }
        }
    }
}

#endif