類型“類”不符合協議“ MCSessionDelegate”

Question

我正在將代碼從Swift 2.X遷移到3.X，並且已經解決了我的大部分運行時錯誤，但其中一個錯誤一直存在。 我具有所有必需的功能，並且已清理並刪除了派生數據，但仍然說我的課程不符合“ MCSessionDelegate”。 `

import MultipeerConnectivity
import Foundation

class Cashier: Advertiser
{
var waiterBecomesConnectedHandler: ((MCPeerID) -> Void)?
var waiterBecomesDisconnectedHandler: ((MCPeerID) -> Void)?
}

extension Cashier: MCSessionDelegate
{

@available(iOS 7.0, *)
func session(_ session: MCSession, didStartReceivingResourceWithName resourceName: String, fromPeer peerID: MCPeerID, with progress: Progress) {

}

@available(iOS 7.0, *)
func session(_ session: MCSession, peer peerID: MCPeerID, didChange state: MCSessionState) {
    switch state {
        case .notConnected:
            waiterBecomesDisconnectedHandler?(peerID)
            connectedPeerSessions.removeValue(forKey: peerID)
            break

        case .connected:
            waiterBecomesConnectedHandler?(peerID)
            break

        case .connecting:
            break
    }
}


@available(iOS 7.0, *)
func session(_ session: MCSession, didReceive data: Data, fromPeer peerID: MCPeerID) {

}

@available(iOS 7.0, *)
func session(_ session: MCSession, didReceive stream: InputStream, withName streamName: String, fromPeer peerID: MCPeerID) {

}


@available(iOS 7.0, *)
func session(_ session: MCSession, didFinishReceivingResourceWithName resourceName: String, fromPeer peerID: MCPeerID, at localURL: URL, withError error: Error?){

}
}`

這是協議的代碼

// Delegate methods for MCSession.
public protocol MCSessionDelegate : NSObjectProtocol {


// Remote peer changed state.
@available(iOS 7.0, *)
public func session(_ session: MCSession, peer peerID: MCPeerID, didChange state: MCSessionState)


// Received data from remote peer.
@available(iOS 7.0, *)
public func session(_ session: MCSession, didReceive data: Data, fromPeer peerID: MCPeerID)


// Received a byte stream from remote peer.
@available(iOS 7.0, *)
public func session(_ session: MCSession, didReceive stream: InputStream, withName streamName: String, fromPeer peerID: MCPeerID)


// Start receiving a resource from remote peer.
@available(iOS 7.0, *)
public func session(_ session: MCSession, didStartReceivingResourceWithName resourceName: String, fromPeer peerID: MCPeerID, with progress: Progress)


// Finished receiving a resource from remote peer and saved the content
// in a temporary location - the app is responsible for moving the file
// to a permanent location within its sandbox.
@available(iOS 7.0, *)
public func session(_ session: MCSession, didFinishReceivingResourceWithName resourceName: String, fromPeer peerID: MCPeerID, at localURL: URL, withError error: Error?)


// Made first contact with peer and have identity information about the
// remote peer (certificate may be nil).
@available(iOS 7.0, *)
optional public func session(_ session: MCSession, didReceiveCertificate certificate: [Any]?, fromPeer peerID: MCPeerID, certificateHandler: @escaping (Bool) -> Swift.Void)
}`

Answer 1

1. 從擴展中刪除所有功能

     extension Cashier: MCSessionDelegate. 

2. 您會看到錯誤缺少子代碼的錯誤，單擊修復選項，它將自動添加所有必需的功能
3. 如果以上兩個步驟均無效，請嘗試清理構建文件夾並重新啟動Xcode

Answer 2

您的委托方法之一是錯誤的。 at localURL: URL應該at localURL: URL?

func session(_ session: MCSession, 
didFinishReceivingResourceWithName resourceName: String, 
    fromPeer peerID: MCPeerID, 
          at localURL: URL?, 
   withError error: Error?)

https://developer.apple.com/documentation/multipeerconnectivity/mcsessiondelegate/1406984-session