UIApplication extension to get app version / build

UIApplication+AppVersion.swift

extension UIApplication {

    class func appVersion() -> String {
        return NSBundle.mainBundle().objectForInfoDictionaryKey("CFBundleShortVersionString") as! String
    }

    class func appBuild() -> String {
        return NSBundle.mainBundle().objectForInfoDictionaryKey(kCFBundleVersionKey as String) as! String
    }

    class func versionBuild() -> String {
        let version = appVersion(), build = appBuild()

        return version == build ? "v\(version)" : "v\(version)(\(build))"
    }
}