     private func migrateAppiraterKeysIfNecessary() {
 
         let appiraterAlreadyCompletedKey: NSString = keyForArmchairKeyType(.AppiraterMigrationCompleted)
-        var appiraterMigrationAlreadyCompleted = userDefaultsObject?.boolForKey(appiraterAlreadyCompletedKey as String)
+        let appiraterMigrationAlreadyCompleted = userDefaultsObject?.boolForKey(appiraterAlreadyCompletedKey as String)
 
         if let completed = appiraterMigrationAlreadyCompleted {
             if completed {

            }

            for subView in window.subviews {
                var nextResponder: UIResponder? = subView.nextResponder()
                if let responder = nextResponder {
                    if responder.isKindOfClass(UIViewController) {
                        return topMostViewController(responder as? UIViewController)
                    }

        }

        // check if the user has done enough significant events
        let significantEventCount = userDefaultsObject?.integerForKey(keyForArmchairKeyType(ArmchairKey.SignificantEventCount))
        if let count = significantEventCount {
            if UInt(count) < significantEventsUntilPrompt {
                return false
