I get an error "EXC_BAD INSTRUCTION" when defining colorsDictionary constant for background color.

var title: String?
var description: String?
var icon: UIImage?
var largeIcon:UIImage?
var artists: [String] = []
var backgroundColor: UIColor = UIColor.clearColor()

init(Index: Int) {
    let musicLibrary = MusicLibrary().library
    let playlistDictionary = musicLibrary[Index]

    title = playlistDictionary["title"] as! String!
    description = playlistDictionary["description"] as! String!

    let iconName = playlistDictionary["icon"] as! String!
    icon = UIImage(named: iconName)

    let largeIconName = playlistDictionary["largeIcon"] as! String!
    largeIcon = UIImage(named: largeIconName)

    artists += playlistDictionary["artists"] as! [String]

    let colorsDictionary = playlistDictionary["backgroundcolor"] as! [String: CGFloat]
    backgroundColor = rgbFromDictionary(colorsDictionary)
}

func rgbFromDictionary(colorDictionary: [String: CGFloat]) -> UIColor {

    let red = colorDictionary["red"]!
    let green = colorDictionary["green"]!
    let blue = colorDictionary["blue"]!
    let alpha = colorDictionary["alpha"]!

    return UIColor(red: red/255.0, green: green/255.0, blue: blue/255.0, alpha: alpha)
}