额外参数 Swift？

Question

调用中的额外参数'error'

func handleReceivedDataWithNotification(notification:NSNotification){
        let userInfo = notification.userInfo! as Dictionary
        let receivedData:NSData = userInfo["data"] as! NSData

        let message = NSJSONSerialization.JSONObjectWithData(receivedData, options: NSJSONReadingOptions.AllowFragments, error: nil) // This the error line
        let senderPeerId:MCPeerID = userInfo["peerID"] as! MCPeerID
        let senderDisplayName = senderPeerId.displayName

        if message.objectForKey("string")?.isEqualToString("New Game") == true{
            let alert = UIAlertController(title: "TicTacToe", message: "\(senderDisplayName) has started a new Game", preferredStyle: UIAlertControllerStyle.Alert)

            alert.addAction(UIAlertAction(title: "OK", style: UIAlertActionStyle.Default, handler: nil))

            self.presentViewController(alert, animated: true, completion: nil)

            resetField()
        }else{
            var field:Int? = message.objectForKey("field")?.integerValue
            var player:String? = message.objectForKey("player") as? String

            if field != nil && player != nil{
                fields[field!].player = player
                fields[field!].Player(player!)

                if player == "x"{
                    currentPlayer = "o"
                }else{
                    currentPlayer = "x"
                }

                checkResults()

            }

        }


    }

Answer 1

您可能正在尝试将 Swift 1.x 调用与 Swift 2.x 编译器一起使用。

Swift 在 1 和 2 之间经历了很大的变化，现在该方法（以及大多数其他报告错误的方法）抛出异常而不是传递错误参数。

current documentation 显示签名为：

 class func JSONObjectWithData(_ data: NSData,
                  options opt: NSJSONReadingOptions) throws -> AnyObject

要了解如何处理异常，请查看 documentation。

额外参数 Swift？

Extra argument Swift?

xcode

ios

swift

swift2.2