iOS MultipeerConnectivity

• 问题

  承接上文[iOS实现WIFI传书]，如果去掉局域网会如何？能否实现设备间文件传输

  iOS设备间的数据传输常用方式：

    1.蓝牙
    2.airdrop
    3.MultipeerConnectivity
  

  该篇单讲MultipeerConnectivity

• 上菜

  设备作为服务端

  • 要有一个标志自己的PeerID

  lazy var me: MCPeerID = {
      let peer = MCPeerID(displayName: UIDevice.current.name)
      return peer
  }()
  

  • 一个session

  lazy var session: MCSession = {
      let ss = MCSession(peer: me, securityIdentity: nil, encryptionPreference: .none)
      ss.delegate = self
      return ss
  }()
  

  • 广播出去，其他设备才能搜索到

  lazy var advertiser: MCNearbyServiceAdvertiser = {
      let advertiser = MCNearbyServiceAdvertiser(peer: me, discoveryInfo: ["demo": "data"], serviceType: "shanzhai")
      advertiser.delegate = self
      return advertiser
  }()
  

  • 开始广播

  advertiser.startAdvertisingPeer()
  

  • 广播的代理方法执行

  extension MultipeerConnectVC: MCNearbyServiceAdvertiserDelegate {
      func advertiser(_ advertiser: MCNearbyServiceAdvertiser, didReceiveInvitationFromPeer peerID: MCPeerID, withContext context: Data?, invitationHandler: @escaping (Bool, MCSession?) -> Void) {
          // 确认连接，赋值session
          invitationHandler(true, session)
      }
      
      func advertiser(_ advertiser: MCNearbyServiceAdvertiser, didNotStartAdvertisingPeer error: Error) {
          advertiser.stopAdvertisingPeer()
          print("Woops! Advertising failed with error \(String(describing: error))")
      }
  }
  

  设备作为客户端

  • 要有一个标志自己的PeerID

  lazy var me: MCPeerID = {
      let peer = MCPeerID(displayName: UIDevice.current.name)
      return peer
  }()
  

  • 一个session

  lazy var session: MCSession = {
      let ss = MCSession(peer: me, securityIdentity: nil, encryptionPreference: .none)
      ss.delegate = self
      return ss
  }()
  

  • 需要一个搜索PeerID

  lazy var browser: MCNearbyServiceBrowser = {
      let bs = MCNearbyServiceBrowser(peer: me, serviceType: "shanzhai")
      bs.delegate = self
      return bs
  }()
  

  • 开始搜索

  browser.startBrowsingForPeers()
  

  • 代理中检索到附近的PeerID, 检索到可以自己存下来，也可以直接链接，依业务需求来，此处直连

  extension MultipeerConnectVC: MCNearbyServiceBrowserDelegate {
      func browser(_ browser: MCNearbyServiceBrowser, foundPeer peerID: MCPeerID, withDiscoveryInfo info: [String : String]?) {
          print("search peerId = \(peerID)")
          //搜到了peerID可以放入数组中，选择想要连接的peerID连接，这里直接连接
          browser.invitePeer(peerID, to: session, withContext: nil, timeout: 10)
      }
      
      func browser(_ browser: MCNearbyServiceBrowser, lostPeer peerID: MCPeerID) {
          print("lost peerID = \(peerID)")
      }
      
      func browser(_ browser: MCNearbyServiceBrowser, didNotStartBrowsingForPeers error: Error) {
          print("error = \(error)")
      }
  }
  

  连接过程看Session，session代理中看各个过程

  extension MultipeerConnectVC: MCSessionDelegate {
  
      func session(_ session: MCSession, peer peerID: MCPeerID, didChange state: MCSessionState) {
      }
      
      func session(_ session: MCSession, didReceive data: Data, fromPeer peerID: MCPeerID) {
          
      }
      
      func session(_ session: MCSession, didReceive stream: InputStream, withName streamName: String, fromPeer peerID: MCPeerID) {
          
      }
      
      func session(_ session: MCSession, didStartReceivingResourceWithName resourceName: String, fromPeer peerID: MCPeerID, with progress: Progress) {
      }
      
      func session(_ session: MCSession, didFinishReceivingResourceWithName resourceName: String, fromPeer peerID: MCPeerID, at localURL: URL?, withError error: Error?) { 
  
      }
  }
  

  • 代理方法didChange didChange方法中 MCSessionState == .connected，表示连接上，连接上后可传递数据

  • 代理方法didFinishReceivingResourceWithName，可以查看接收到的数据

  • 也可使用MCBrowserViewController，搜索到的PeerID，无需自己写界面

• 结语

  该方式并未打通iOS与Android，适用于苹果设备之间的无网络数据传输。FileChat在苹果设备之间的实现方式应该是基于此进行的