xcode - 尝试在 Swift 的多点连接测试应用程序中使用 NSNotification

Question

一直在学习本教程:

http://www.appcoda.com/intro-multipeer-connectivity-framework-ios-programming/

但一直在将其转换为在 Swift 中工作。然而，在以下方面出现了问题:

-(void)peerDidChangeStateWithNotification:(NSNotification *)notification
    {
        MCPeerID *peerID = [[notification userInfo] objectForKey:@"peerID"];
        NSString *peerDisplayName = peerID.displayName;
        MCSessionState state = [[[notification userInfo] objectForKey:@"state"] intValue];

这是造成麻烦的最后一行，我已经走到这一步了:

func peerDidChangeStateWithNotification(notification: NSNotification)
{
    if let userInfo : AnyObject = notification.userInfo? {
        let peerID = userInfo["peerID"] as MCPeerID
        let state = userInfo["state"] as MCSessionState

但是无法将“state”条目获取到 MCSessionState 类型中，出现错误:

'AnyObject' is not convertible to 'MCSessionState'

谁能帮忙……？对 Swift 很陌生，很抱歉，如果这是一个明显的问题......

非常感谢，佛朗哥。

---

9 月 9 日更新:

首先设置 userInfo 对象的代码如下，据我所知调用 toRaw() 方法应该只是意味着它把它当作存储一个 Int ...？在这种情况下，我不知道为什么您的原始答案不起作用...

func session(session: MCSession!, peer peerID: MCPeerID!, didChangeState state: MCSessionState)
{

    var dict = ["peerID": peerID, "state": state.toRaw()]

    NSNotificationCenter.defaultCenter().postNotificationName("MCDidChangeStateNotification", object: nil, userInfo: dict)

}

---

9 月 2 日更新:

知道了!如果其他人正在遵循同一教程，则转换函数的完整工作版本如下所示。非常感谢埃德温·维米尔 (Edwin Vermeer) 的帮助:

func peerDidChangeStateWithNotification(notification: NSNotification)
{
    if let userInfo : AnyObject = notification.userInfo?
    {
        let peerID = userInfo["peerID"] as MCPeerID
        let peerDisplayName = peerID.displayName
        let state: MCSessionState = MCSessionState.fromRaw(Int(userInfo["state"] as NSNumber)) as MCSessionState!

        if (state != MCSessionState.Connecting)
        {
            if (state == MCSessionState.Connected)
            {
                arrayConnectedDevices.append(peerDisplayName)
            }
            else if (state == MCSessionState.NotConnected)
            {
                if (arrayConnectedDevices.count > 0)
                {
                    if let i = find(arrayConnectedDevices, peerDisplayName)
                    {
                        arrayConnectedDevices.removeAtIndex(i)
                    }
                }
            }
        }
    }
}

Answer 1

您可以使用它来将 int 转换为枚举:

let state: MCSessionState = MCSessionState.fromRaw(Int(userInfo["state"] as NSNumber)) as MCSessionState!