swift - MCSessionState 从连接状态变为未连接状态

Question

每当我尝试使用Multipeer Connectivity Framework连接对等点时，对等点的状态会从MCSessionState.Connecting变为MCSessionState.NotConnected。

以下是我运行的事件顺序：

1. 模拟器通过MCNearbyServiceAdvertiser宣传该服务。
2. iPhone 通过MCNearbyServiceBrowser浏览服务。
3. iPhone 找到模拟器并立即通过invitePeer(_:toSession:withContext:timeout:)将其邀请到会话中。
4. 最后，模拟器使用 ads(_:didReceiveInvitationFromPeer:withContext:invitationHandler:)接受邀请。

笔记：

• 即使我不需要安全性，我也会接受客户发送的任何证书，以防出现错误。

这是我正在使用的代码：

import UIKit
import MultipeerConnectivity

class ViewController: UIViewController {
    var advertiser: MCNearbyServiceAdvertiser!
    var browser: MCNearbyServiceBrowser!
    var session: MCSession!

    override func viewDidLoad() {
        super.viewDidLoad()
        let localPeerID = MCPeerID(displayName: UIDevice.currentDevice().name)
        session = MCSession(peer: localPeerID, securityIdentity: nil, encryptionPreference: MCEncryptionPreference.None)
        session.delegate = self
    }

    @IBAction func hostTapped(sender: AnyObject) {
        let localPeerID = MCPeerID(displayName: UIDevice.currentDevice().name)
        advertiser = MCNearbyServiceAdvertiser(peer: localPeerID, discoveryInfo: nil, serviceType: "abc")
        advertiser.delegate = self
        print("started advertising")
        advertiser.startAdvertisingPeer()
    }

    @IBAction func connectTapped(sender: AnyObject) {
        let localPeerID = MCPeerID(displayName: UIDevice.currentDevice().name)
        browser = MCNearbyServiceBrowser(peer: localPeerID, serviceType: "abc")
        browser.delegate = self
        print("started searching")
        browser.startBrowsingForPeers()
    }
}

extension ViewController: MCNearbyServiceAdvertiserDelegate {
    func advertiser(advertiser: MCNearbyServiceAdvertiser, didReceiveInvitationFromPeer peerID: MCPeerID, withContext context: NSData?, invitationHandler: (Bool, MCSession) -> Void) {
        print("accepting invitation from \(peerID.displayName)")
        invitationHandler(true, session)
    }

    func advertiser(advertiser: MCNearbyServiceAdvertiser, didNotStartAdvertisingPeer error: NSError) {
        print("did not start advertising \(error)")
    }
}

extension ViewController: MCSessionDelegate {
    func session(session: MCSession, peer peerID: MCPeerID, didChangeState state: MCSessionState) {
        print("\(peerID.displayName) changed state: \(state.toString())")
    }

    func session(session: MCSession, didReceiveData data: NSData, fromPeer peerID: MCPeerID) {

    }

    func session(session: MCSession, didReceiveStream stream: NSInputStream, withName streamName: String, fromPeer peerID: MCPeerID) {

    }

    func session(session: MCSession, didStartReceivingResourceWithName resourceName: String, fromPeer peerID: MCPeerID, withProgress progress: NSProgress) {

    }

    func session(session: MCSession, didFinishReceivingResourceWithName resourceName: String, fromPeer peerID: MCPeerID, atURL localURL: NSURL, withError error: NSError?) {

    }

    func session(session: MCSession, didReceiveCertificate certificate: [AnyObject]?, fromPeer peerID: MCPeerID, certificateHandler: (Bool) -> Void) {
        certificateHandler(true)
    }
}

extension ViewController: MCNearbyServiceBrowserDelegate {
    func browser(browser: MCNearbyServiceBrowser, foundPeer peerID: MCPeerID, withDiscoveryInfo info: [String : String]?) {
        print("found \(peerID.displayName), inviting to session")
        browser.invitePeer(peerID, toSession: session, withContext: nil, timeout: 30)
    }

    func browser(browser: MCNearbyServiceBrowser, lostPeer peerID: MCPeerID) {
        print("lost \(peerID.displayName)")
    }
}

extension MCSessionState {
    func toString() -> String {
        switch self {
        case .Connected:    return "Connected"
        case .Connecting:   return "Connecting"
        case .NotConnected: return "Not Connected"
        }
    }
}

这里有一个类似的问题，但是，链接的代码很旧，无法再访问。此外，问题在于使用了相同的会话对象。

Answer 1

我为 MCSession、MCNearbyServiceAdvertiser 和 MCNearbyServiceBrowser使用了不同的MCPeerID实例。

为了解决这个问题，我创建了一个 MCPeerID 实例变量：

var localPeerID: MCPeerID?

override func viewDidLoad() {
    // ...
    localPeerID = MCPeerID(displayName: UIDevice.currentDevice().name)
    // ...
}

...并使用它而不是将它们创建为局部变量（let localPeerID = ...）。

现在它正确地从连接状态变为连接状态。

Answer 2

总是可以将它创建为类的常量！

class ViewController: UIViewController {
    var advertiser: MCNearbyServiceAdvertiser!
    var browser: MCNearbyServiceBrowser!
    var session: MCSession!

    let localPeerID = MCPeerID(displayName: UIDevice.currentDevice().name)
    ...
}