Swift enum segmentation fault

问题

I have to following code:

groupListeningObject = NSNotificationCenter.defaultCenter().addObserverForName(groupJoinedOrLeftNotificationName, object: nil, queue: nil) { [weak self] notification in
    if let notificationArray = notification.object as? [AnyObject]  {
        let joinedOrLeft = JoinOrLeave(rawValue: notificationArray[1] as Int)
        if joinedOrLeft == .Join {
            //some code
        } 
    }
}

This gives a segmentation fault error, but if I modify the if statement as follows:

if joinedOrLeft == JoinOrLeave.Join

there will be no error. I thought I can use the short version of an enum in an if statement, but the compiler doesn't like it. Why can't I use the shorter version of enums, what am I missing here?

来源：https://stackoverflow.com/questions/28559192/swift-enum-segmentation-fault