在GameScene中显示UIAlertController(SpriteKit/Swift)

Question

在swift中显示UIAlertView的简单方法是:

let alert = UIAlertView()
alert.title = "Alert!"
alert.message = "A wise message"
alert.addButtonWithTitle("Ok, thank you")
alert.show()

但现在这在iOS 9中已经过折旧,建议使用UIAlertController:

let myAlert: UIAlertController = UIAlertController(title: "Alert!", message: "Oh! Fancy", preferredStyle: .Alert)
myAlert.addAction(UIAlertAction(title: "OK", style: .Default, handler: nil))
self.presentViewController(myAlert, animated: true, completion: nil)

哪个好,但我在使用SpriteKit并在GameScene中,这给出了一个错误Value of type 'GameScene' has no member 'presentViewController'...

我是否需要切换回我的ViewController来呈现这个或者有没有办法从GameScene中调用它.

我找到了这个答案,但它是Objective-C.

Answer 1

有很多方法可以处理这种情况,我不建议使用Jozemite Apps答案,因为这会导致有超过1个视图控制器的应用程序出现问题.(您希望在当前视图控制器上显示警报,而不是根目录)

我这样做的首选方式是通过授权.需要做的是创建一个处理消息传递的协议:

import Foundation
protocol ViewControllerDelegate
{
    func sendMessage(message:String);
}

在您的视图控制器中:

class ViewController : UIViewController, ViewControllerDelegate
{
    ...
    func sendMessage(message:String)
    {
       //do alert view code here
    }

    //in the view controllers view did load event
    func viewDidLoad()
    {
        var view = self.view as! GameSceneView
        view.delegate = self
    }

在您的视图代码中:

  var delegate : ViewControllerDelegate

最后在你想要呈现的游戏场景中:

self.view.delegate?.sendMessage(message)

这种方式允许对VC的有限访问,并且可以在需要时使用更多选项进行修改.

另一种方法是建立一个通知系统,并使用NSNotificationCenter将消息从场景传递给当前VC并让它发送消息;

在ViewController中

func viewDidLoad()
{
  NSNotificationCenter.defaultCenter().addObserver(self,selector:"AlertMessage:",name:"AlertMessage",object:nil);

}

func AlertMessage(notification:NSNotification)
{
    if(let userInfo = notification.userInfo)
    {
      let message = userInfo["message"]
      ....//do alert view call here
    }
}

在游戏场景代码中:

...at the spot you want to send a message
let userInfo = ["message":message];
NSNotificationCenter.defaultCenter.postNotificationNamed("AlertMessage",object:nil,userInfo:userInfo)

另一种方法是将视图控制器指针保存到游戏场景视图:

//in Game Scene View code
var viewController : UIViewController; 

//in the view controllers view did load event
func viewDidLoad()
{
    var view = self.view as! GameSceneView
    view.viewController = self
}

//finally in game scene where you want to present
let myAlert: UIAlertController = UIAlertController(title: "Alert!", message: "Oh! Fancy", preferredStyle: .Alert)
myAlert.addAction(UIAlertAction(title: "OK", style: .Default, handler: nil))
self.view.viewController.presentViewController(myAlert, animated: true, completion: nil)

另一种方法是使视图控制器全局化.

在视图控制器代码中:private var _instance:UIViewController

class ViewController : UIViewController
{
    class var instance
    {
        get
        {
            return _instance;
        }
    }

    func viewDidLoad()
    {
       _instance = self;
    }
}

然后打电话

ViewController.instance!.  

每当您需要访问视图控制器时.

这些方法中的每一种都有优点和缺点,因此请选择最适合您的方法.