Swift UIButton subclass that implements toggle and backgroundColor for states

QButton.swift

import UIKit

class QButton: UIButton {
    var isToggle: Bool = false {
        didSet {
            if isToggle {
                self.addTarget(self, action: Selector("touchUpInside:"), forControlEvents: .TouchUpInside)
            } else {
                self.removeTarget(self, action: Selector("touchUpInside:"), forControlEvents: .TouchUpInside)
            }
        }
    }
    var backgroundColorNormal: UIColor? {
        didSet {
            backgroundColor = backgroundColorNormal
        }
    }
    var backgroundColorHighlighted: UIColor?
    var _backgroundColorHighlighted: UIColor? {
        return backgroundColorHighlighted != nil ? backgroundColorHighlighted : backgroundColorNormal
    }
    var backgroundColorSelected: UIColor?
    var _backgroundColorSelected: UIColor? {
        return backgroundColorSelected != nil ? backgroundColorSelected : _backgroundColorHighlighted
    }
    var backgroundColorHighlightedSelected: UIColor?
    var _backgroundColorHighlightedSelected: UIColor? {
        return backgroundColorHighlightedSelected != nil ? backgroundColorHighlightedSelected : _backgroundColorHighlighted
    }
    
    override var highlighted: Bool {
        didSet {
            switch (highlighted, selected) {
            case (true, false):
                backgroundColor = _backgroundColorHighlighted
            case (true, true):
                backgroundColor = _backgroundColorHighlightedSelected
            case (false, true):
                backgroundColor = _backgroundColorSelected
            default:
                backgroundColor = backgroundColorNormal
            }
        }
    }
    
    func touchUpInside(sender: UIButton!) {
        selected = ~selected
    }
}

//    func setBGColor(color: UIColor?, forState state: UIControlState) {
//        switch state {
//        case UIControlState.Highlighted:
//            println("normal")
//        case UIControlState.Selected:
//            println("normal")
//        case UIControlState.Normal:
//            println("normal")
//        case UIControlState.Highlighted | UIControlState.Selected:
//            println("normal")
//        default: break
//        }
//    }