利用Multipeer Connectivity框架进行WiFi传输-b

什么是Multipeer Connectivity？

在iOS7中，引入了一个全新的框架——Multipeer Connectivity（多点连接）。利用Multipeer Connectivity框架，即使在没有连接到WiFi（WLAN）或移动网络（xG）的情况下，距离较近的Apple设备（iMac/iPad/iPhone）之间可基于蓝牙和WiFi（P2P WiFi）技术进行发现和连接实现近场通信。

Multipeer Connectivity扩充的功能与利用AirDrop传输文件非常类似，可以将其看作AirDrop不能直接使用的补偿，代价是需要自己实现。

本Demo主要用到4个类：
MCBrowserViewController:MCBrowserViewController继承自UIViewController，提供了基本的UI应用框架。

MCAdvertiserAssistant、MCAdvertiserAssistant为针对Advertiser封装的管理助手,主要处理广播信息。

MCSession:类似TCP链接中的socket。创建MCSession时，需指定自身MCPeerID，类似bind。

MCPeerID:类似sockaddr，用于标识连接的两端endpoint，通常是昵称或设备名称。

1、简单地建立一个界面，主要有连接和发送2个UIButton。

create_button.png

2、Multipeer Connectivity框架初始化这4个类。

#pragma mark - Wifi Sharing Methods-(void)setUpMultipeer {    //  Setup peer ID     self.myPeerID = [[MCPeerID alloc] initWithDisplayName:[UIDevice currentDevice].name];    //  Setup session     self.mySession = [[MCSession alloc] initWithPeer:self.myPeerID];    self.mySession.delegate = self;    //  Setup BrowserViewController     self.browserVC = [[MCBrowserViewController alloc] initWithServiceType:@"chat" session:self.mySession];    self.browserVC.delegate = self;    //  Setup Advertiser     self.advertiser = [[MCAdvertiserAssistant alloc] initWithServiceType:@"chat" discoveryInfo:nil session:self.mySession];     [self.advertiser start]; }  -(void)showBrowserVC {     [self presentViewController:self.browserVC animated:YES completion:nil]; }  -(void)dismissBrowserVC {     [self.browserVC dismissViewControllerAnimated:YES completion:^(void){         [self invokeAlertMethod:@"连接成功" Body:@"Both device connected successfully." Delegate:nil];     }]; }  -(void)stopWifiSharing:(BOOL)isClear {    if(isClear && self.mySession != nil){         [self.mySession disconnect];          [self.mySession setDelegate:nil];        self.mySession = nil;        self.browserVC = nil;     } }

 

3、MCBrowserViewController代理方法

#pragma marks MCBrowserViewControllerDelegate// 点击完成-(void)browserViewControllerDidFinish:(MCBrowserViewController *)browserViewController {     [self dismissBrowserVC];     [marrReceiveData removeAllObjects]; }// 点击取消-(void)browserViewControllerWasCancelled:(MCBrowserViewController *)browserViewController {     [self dismissBrowserVC]; }

 

4、MCSession代理方法
主要处理发送方传递的文件或者信息

// Received data from remote peer- (void)session:(MCSession *)session didReceiveData:(NSData *)data fromPeer:(MCPeerID *)peerID {    NSLog(@"data receiveddddd : %lu",(unsigned long)data.length);    if (data.length > 0) {        if (data.length < 2) {             noOfDataSend++;            NSLog(@"noofdatasend : %zd",noOfDataSend);            NSLog(@"array count : %zd",marrFileData.count);            if (noOfDataSend < ([marrFileData count])) {                 [self.mySession sendData:[marrFileData objectAtIndex:noOfDataSend] toPeers:[self.mySession connectedPeers] withMode:MCSessionSendDataReliable error:nil];             }else {                 [self.mySession sendData:[@"File Transfer Done" dataUsingEncoding:NSUTF8StringEncoding] toPeers:[self.mySession connectedPeers] withMode:MCSessionSendDataReliable error:nil];             }         } else {            if ([[[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding] isEqualToString:@"File Transfer Done"]) {                 [self appendFileData];             }else {                 [self.mySession sendData:[@"1" dataUsingEncoding:NSUTF8StringEncoding] toPeers:[self.mySession connectedPeers] withMode:MCSessionSendDataReliable error:nil];                 [marrReceiveData addObject:data];             }         }     } }// Received a byte stream from remote peer- (void)session:(MCSession *)session didReceiveStream:(NSInputStream *)stream withName:(NSString *)streamName fromPeer:(MCPeerID *)peerID {    NSLog(@"did receive stream"); }// Start receiving a resource from remote peer- (void)session:(MCSession *)session didStartReceivingResourceWithName:(NSString *)resourceName fromPeer:(MCPeerID *)peerID withProgress:(NSProgress *)progress {    NSLog(@"start receiving"); }// 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- (void)session:(MCSession *)session didFinishReceivingResourceWithName:(NSString *)resourceName fromPeer:(MCPeerID *)peerID atURL:(NSURL *)localURL withError:(NSError *)error {    NSLog(@"finish receiving resource"); }  -(void)session:(MCSession *)session peer:(MCPeerID *)peerID didChangeState:(MCSessionState)state {    NSLog(@"change state : %zd",state); }

5、发送图片（此Demo只是简单地做了个收发图片的Demo，此框架可实现的功能当然不止这么简单。）

-(void)sendData {     [marrFileData removeAllObjects];    NSData *sendData = UIImagePNGRepresentation([UIImage imageNamed:@"test2.png"]);    NSUInteger length = [sendData length];    NSUInteger chunkSize = 100 * 1024;    NSUInteger offset = 0;    do {        NSUInteger thisChunkSize = length - offset > chunkSize ? chunkSize : length - offset;        NSData* chunk = [NSData dataWithBytesNoCopy:(char *)[sendData bytes] + offset                                              length:thisChunkSize                                        freeWhenDone:NO];        NSLog(@"chunk length : %lu",(unsigned long)chunk.length);          [marrFileData addObject:[NSData dataWithData:chunk]];         offset += thisChunkSize;     } while (offset < length);      noOfdata = [marrFileData count];     noOfDataSend = 0;    if ([marrFileData count] > 0) {         [self.mySession sendData:[marrFileData objectAtIndex:noOfDataSend] toPeers:[self.mySession connectedPeers] withMode:MCSessionSendDataReliable error:nil];     } }  -(void)appendFileData {    NSMutableData *fileData = [NSMutableData data];    for (int i = 0; i < [marrReceiveData count]; i++) {         [fileData appendData:[marrReceiveData objectAtIndex:i]];     }      [fileData writeToFile:[NSString stringWithFormat:@"%@/Image.png", [NSHomeDirectory() stringByAppendingPathComponent:@"Documents"]] atomically:YES];    UIImageWriteToSavedPhotosAlbum([UIImage imageWithData:fileData], self, @selector(image:didFinishSavingWithError:contextInfo:), nil); }  - (void)image:(UIImage *)image didFinishSavingWithError:(NSError *)error contextInfo:(void *)contextInfo {    if (!error) {         [self invokeAlertMethod:@"发送成功" Body:@"图片已保存到手机相册" Delegate:nil];     } }

您可在Github上下载完整Demo: https://github.com/JanzTam/WiFiShareDemo。