If variables, with primitive types like Int, are not atomic by default in Swift , is this the best to mimic "@synchronize" behavior?

Question

I am using GCD's "dispatch_apply", implementing a for - loop parallelism. I have "score" variable, defined outside the loop and I need it to be atomic. In objective C we used to have this @atomic keyword, but I don't see it in swift. Are all primitive type variables atomic by default? So far I haven't seen a conclusive answer for Swift 2.0.

Edit : I have decided to use GCD and dispatch_sync. Could somebody comment if my solution is thread safe?

let queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
    let lockQueue = dispatch_queue_create("com.test.LockQueue", nil)
    
        
        var bestScore = Int.min
        var bestLocation: BoardLocation?
        let possibleMoves = board.getPossibleMoves()

        let i = 0
        let count = possibleMoves?.count ?? 0
        //using parralel loop
        dispatch_apply(count, queue) { (  let i : size_t) in
                        let nextMove : BoardLocation = possibleMoves![i] as! BoardLocation
            // clone the current board and make the move
            let testBoard = ReversiBoard(board: self.board)
            testBoard.makeMove(nextMove)
            
            
            // if we can slay the opponent we do it no evaluation required
            if (testBoard.gameHasFinished == true){
                dispatch_sync(lockQueue) {
                    bestLocation = nextMove
                    bestScore =  Int.max
                }
     
              //  break
            }
            
         let scoreForMove : Int =  self.alphaBetaEvaluateWithState(testBoard,depth: startDepth)
            dispatch_sync(lockQueue) {

            if (scoreForMove > bestScore) {
                bestScore = scoreForMove
                bestLocation = nextMove
            }
            }
            
            
        }
        
        if bestScore > Int.min {
            
            dispatch_async(dispatch_get_main_queue(), {
                self.board.makeMove(bestLocation!)                    
            })
            
        }
        
    }