ios开发cocoaAsyncSocket与protobuf的使用swift5版本，含粘包拆包

╰半夏微凉° 2021-11-05 23:12 585阅读 0赞

最近搞了一下即时通讯，为了配合服务器的使用（netty4+protobuf3)，在ios客户端捣鼓了一下。

在ios客户端使用protobuf的资料比较少，配合cocoaAsyncSocket使用的更少，swift版本的更加少。

在swift版本中有处理protobuf粘包/拆包的资料基本没有。所以分享一下，希望对一些朋友有帮助

1、首先导入必要的包。

这里使用了Carthage作为管理，分别导入cocoaAsyncSocket和protobuf

//在swift中使用protobuf需要导入swift-protobuf
    github "apple/swift-protobuf" ~> 1.0
    github "robbiehanson/CocoaAsyncSocket" "master"

如何生成proto文件，这里不介绍，可以自行参考：[https://github.com/apple/swift-protobuf][https_github.com_apple_swift-protobuf]

2、直接上关键代码，注释已经写的非常清楚了。

//
    //  SocketClient.swift
    //  BestTravel
    //
    //  Created by gj on 16/11/1.
    //
    //
    
    import UIKit
    import SwiftProtobuf
    
    class SocketClient: NSObject{
        
        fileprivate var clientSocket: GCDAsyncSocket!
        //数据缓冲
        fileprivate var receiveData:Data=Data.init();
      
        //单例模式
        static let sharedInstance=SocketClient();
        private override init() {
            super.init();
            clientSocket = GCDAsyncSocket(delegate: self, delegateQueue: DispatchQueue.main)
        }
        
        
    }
    
    extension SocketClient {
        // 开始连接
        func startConnect(){
            startReConnectTimer();
        }
        
        //断开连接
        func stopConnect(){
            if(clientSocket.isConnected){
                clientSocket.disconnect()
            }
        }
        
    
    }
    
    //MARK: 监听
    extension SocketClient: GCDAsyncSocketDelegate {
        
        // 断开连接
        func socketDidDisconnect(_ sock: GCDAsyncSocket, withError err: Error?) {
            
        }
        
        // 连接成功
        func socket(_ sock: GCDAsyncSocket, didConnectToHost host: String, port: UInt16) {
       
            
        }
        
        
        // 接收到消息
        func socket(_ sock: GCDAsyncSocket, didRead data: Data, withTag tag: Int) {
            
            //接收数据放入缓冲区
            self.receiveData.append(data);
            
            //读取data的头部占用字节 和 从头部读取内容长度
            //验证结果：数据比较小时头部占用字节为1，数据比较大时头部占用字节为2
            var headL:Int  = 0;
            let contentL:Int32 = try! ReadRawVarint32Decode.readRawVarint32(buffer: [UInt8](data), bufferPos: &headL)
            
            //如果没有内容，继续接收
            if (contentL < 1){
                sock.readData(withTimeout: -1, tag: 0);
                return;
            }
            
            //拆包情况下：继续接收下一条消息，直至接收完这条消息所有的拆包，再解析
            if (Int32(headL) + contentL > self.receiveData.count){
                sock.readData(withTimeout: -1, tag: 0);
                return;
            }
            
            //当receiveData长度不小于第一条消息内容长度时，开始解析receiveData
            self.parseContentData(headL: Int32(headL), contentL: contentL);
            sock.readData(withTimeout: -1, tag: 0);
        }
        
        
        
        //-----------------------------------------------------------------------------
        
        
        /** 解析二进制数据：NSData --> 自定义模型对象 */
        func parseContentData( headL: Int32, contentL: Int32) {
          
            let range = Range(0...Int(headL + contentL-1)) //本次解析data的范围
            let data = receiveData.subdata(in: range) //本次解析的data
            
            do {
                //把消息转成stream
                let stream = InputStream.init(data: data);
                stream.open()
                var message = Message();
                //注意这段很重要，必须要粘包才能正常解析
                try BinaryDelimited.merge(into:&message, from: stream)
                stream.close();
                
                //处理消息,这可以写你的代码，比如把消息传出去
                
                
                //移除已经解析过的data，避免消息重复解析
                receiveData.removeSubrange(range)
                if (receiveData.count < 1) {
                    return
                }
                
                //对于粘包情况下被合并的多条消息，循环递归直至解析完所有消息
                var headL:Int = 0
                let contentL = try ReadRawVarint32Decode.readRawVarint32(buffer: [UInt8](receiveData), bufferPos: &headL)
                if headL + Int(contentL) > receiveData.count {
                    return //实际包不足解析，继续接收下一个包
                }
                
            } catch  {
                print(error)
            }
            
            parseContentData(headL: headL, contentL: contentL) //继续解析下一条
        }
        
        
        
    }

3、这里有个非常关键的类，上用来判断prototbuf消息的，网上基本找不到swift版本的，倒是有个objc的版本。这里放一个自己写的swift版本的：

//
    //  SocketDelegate.swift
    //  gim
    //
    //  Created by imac on 2019/6/21.
    //  Copyright © 2019 gim. All rights reserved.
    //
    
    import UIKit
    
    
    class ReadRawVarint32Decode: NSObject {
        
        //static var bufferPos:Int = 0
        
        class  func readRawVarint32(buffer:[UInt8],bufferPos:inout Int) throws -> Int32 {
            var tmp = try readRawByte(buffer: buffer,bufferPos: &bufferPos);
            if (tmp >= 0) {
                return Int32(tmp);
            }
            var result : Int32 = Int32(tmp) & 0x7f;
            tmp = try readRawByte(buffer: buffer,bufferPos: &bufferPos)
            if (tmp >= 0) {
                result |= Int32(tmp) << 7;
            } else {
                result |= (Int32(tmp) & 0x7f) << 7;
                tmp = try readRawByte(buffer: buffer,bufferPos: &bufferPos)
                if (tmp >= 0) {
                    result |= Int32(tmp) << 14;
                } else {
                    result |= (Int32(tmp) & 0x7f) << 14;
                    tmp = try readRawByte(buffer: buffer,bufferPos: &bufferPos)
                    if (tmp >= 0) {
                        result |= Int32(tmp) << 21;
                    } else {
                        result |= (Int32(tmp) & 0x7f) << 21;
                        tmp = try readRawByte(buffer: buffer,bufferPos: &bufferPos)
                        result |= (Int32(tmp) << 28);
                        if (tmp < 0) {
                            // Discard upper 32 bits.
                            for _ in 0..<5 {
                                let byte = try readRawByte(buffer: buffer,bufferPos: &bufferPos)
                                if (byte >= 0) {
                                    return result;
                                }
                            }
                            
                            throw ProtocolBuffersError.invalidProtocolBuffer("MalformedVarint")
                        }
                    }
                }
            }
            return result;
        }
        
        class func readRawByte(buffer:[UInt8], bufferPos:inout Int) throws -> Int8 {
            if (bufferPos == buffer.count) {
                return -1
            }
            let res = buffer[Int(bufferPos)]
            bufferPos+=1
            
            var convert:Int8 = 0
            convert = convertTypes(convertValue: res, defaultValue: convert)
            return convert
        }
        
        
        class  func convertTypes<T, ReturnType>(convertValue value:T, defaultValue:ReturnType) -> ReturnType
        {
            var retValue = defaultValue
            var curValue = value
            memcpy(&retValue, &curValue, MemoryLayout<T>.size)
            return retValue
        }
        
        
        
        
        
        public enum ProtocolBuffersError: Error {
            case obvious(String)
            //Streams
            case invalidProtocolBuffer(String)
            case illegalState(String)
            case illegalArgument(String)
            case outOfSpace
        }
        
    }

4、还有一点要非常注意，因为消息通过二进制传输，所以发的时候，也需要先进行encode,比如如果每次发送的字节上1024，但你的消息长度超过1024，那么消息就会被分包发送，如果不先进行encode。那么接收解析就会有问题。因此，在创建消息的时候，应该要加上protobuf的消息头，看代码：

var messageBuilder = Message.init();
      //消息要通过以下方式转成data,否则解析会有问题
     let stream1 = OutputStream.toMemory()
                stream1.open()
                //关键
                try BinaryDelimited.serialize(message: messageBuilder, to: stream1);
                stream1.close()
                //转成data
                let nsData = stream1.property(forKey: .dataWrittenToMemoryStreamKey) as! NSData
                data = Data(referencing: nsData)

到此，基本上跟服务器端的收发已经完成不是问题了。

源码地址：[https://github.com/gogym/gim-ios-sdk][https_github.com_gogym_gim-ios-sdk]

[https_github.com_apple_swift-protobuf]: https://github.com/apple/swift-protobuf
[https_github.com_gogym_gim-ios-sdk]: https://github.com/gogym/gim-ios-sdk