iOS上使用WebRTC推拉流的案例

SY.ZHOU2025-07-25 16:11

一、库集成

首先，确保在你的 Podfile 中添加依赖：

复制代码 
pod 'GoogleWebRTC'

然后执行 pod install 安装库。

二、代码示例

2.1、权限配置：在 Info.plist 中添加摄像头、麦克风权限

复制代码 
<!-- 需要在 Info.plist 中添加以下权限 -->
<key>NSCameraUsageDescription</key>
<string>需要访问摄像头进行视频通话</string>
<key>NSMicrophoneUsageDescription</key>
<string>需要访问麦克风进行语音通话</string>
<key>NSAppTransportSecurity</key>
<dict>
    <key>NSAllowsArbitraryLoads</key>
    <true/>
</dict>

2.2、代码

核心类oc：WebRTCManager.m

objectivec 复制代码 
#import "WebRTCManager.h"
#import <AVFoundation/AVFoundation.h>

@interface WebRTCManager ()
@property (nonatomic, strong) RTCPeerConnectionFactory *factory;
@property (nonatomic, strong) RTCVideoTrack *localVideoTrack;
@property (nonatomic, strong) RTCAudioTrack *localAudioTrack;
@property (nonatomic, strong) RTCVideoRendererAdapter *localRenderer;
@end

@implementation WebRTCManager

- (instancetype)initWithDelegate:(id<WebRTCManagerDelegate>)delegate {
    self = [super init];
    if (self) {
        _delegate = delegate;
        [self setupPeerConnectionFactory];
        [self setupPeerConnection];
    }
    return self;
}

// 初始化 PeerConnection 工厂
- (void)setupPeerConnectionFactory {
    RTCInitializeSSL();
    _factory = [[RTCPeerConnectionFactory alloc] init];
}

// 配置并创建 PeerConnection
- (void)setupPeerConnection {
    RTCConfiguration *config = [[RTCConfiguration alloc] init];
    config.iceServers = @[
        [[RTCIceServer alloc] initWithURLStrings:@[@"stun:stun.l.google.com:19302"]]
    ];
    
    RTCOfferAnswerOptions *offerAnswerOptions = [[RTCOfferAnswerOptions alloc] init];
    offerAnswerOptions.offerToReceiveAudio = YES;
    offerAnswerOptions.offerToReceiveVideo = YES;
    
    RTCMediaConstraints *constraints = [[RTCMediaConstraints alloc] initWithMandatoryConstraints:@[] optionalConstraints:@[]];
    
    _peerConnection = [_factory peerConnectionWithConfiguration:config constraints:constraints delegate:self];
}

// 初始化本地媒体流
- (void)setupLocalStreamWithVideoView:(UIView *)videoView {
    // 请求音视频权限
    [AVCaptureDevice requestAccessForMediaType:AVMediaTypeVideo completionHandler:^(BOOL granted) {
        dispatch_async(dispatch_get_main_queue(), ^{
            if (granted) {
                [self createLocalMediaStream];
                [self setupLocalVideoRender:videoView];
            } else {
                NSLog(@"需要摄像头权限才能使用视频功能");
            }
        });
    }];
}

// 创建本地媒体流
- (void)createLocalMediaStream {
    _localStream = [_factory mediaStreamWithStreamId:@"localStream"];
    
    // 创建音频轨道
    RTCAudioSource *audioSource = [_factory audioSourceWithConstraints:[self defaultMediaConstraints]];
    _localAudioTrack = [_factory audioTrackWithSource:audioSource trackId:@"audio0"];
    [_localStream addAudioTrack:_localAudioTrack];
    
    // 创建视频轨道
    RTCVideoSource *videoSource = [_factory videoSourceWithConstraints:[self videoConstraints]];
    _localVideoTrack = [_factory videoTrackWithSource:videoSource trackId:@"video0"];
    [_localStream addVideoTrack:_localVideoTrack];
    
    // 将本地流添加到 PeerConnection
    [_peerConnection addStream:_localStream];
}

// 设置本地视频渲染
- (void)setupLocalVideoRender:(UIView *)videoView {
    RTCMTLVideoView *rendererView = [[RTCMTLVideoView alloc] init];
    rendererView.frame = videoView.bounds;
    rendererView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
    [videoView addSubview:rendererView];
    
    _localRenderer = [[RTCVideoRendererAdapter alloc] initWithRenderer:rendererView];
    [_localVideoTrack addRenderer:_localRenderer];
}

// 创建 Offer
- (void)createOffer {
    RTCOfferAnswerConstraints *constraints = [[RTCOfferAnswerConstraints alloc] init];
    constraints.mandatoryConstraints = @[
        [[RTCPair alloc] initWithKey:@"OfferToReceiveAudio" value:@"true"],
        [[RTCPair alloc] initWithKey:@"OfferToReceiveVideo" value:@"true"]
    ];
    
    [_peerConnection createOfferWithConstraints:constraints completionHandler:^(RTCSessionDescription * _Nullable sdp, NSError * _Nullable error) {
        if (error) {
            NSLog(@"创建 Offer 失败: %@", error.localizedDescription);
            return;
        }
        
        [self.peerConnection setLocalDescriptionWithSessionDescription:sdp completionHandler:^(NSError * _Nullable error) {
            if (error) {
                NSLog(@"设置本地描述失败: %@", error.localizedDescription);
                return;
            }
            
            // 这里应该将 sdp 发送给信令服务器
            NSString *offerString = [self sessionDescriptionToString:sdp];
            NSLog(@"生成 Offer: %@", offerString);
            // [self.signalingClient sendOffer:offerString];
        }];
    }];
}

// 处理远程 Offer
- (void)handleRemoteOffer:(NSString *)offer {
    RTCSessionDescription *remoteSDP = [self stringToSessionDescription:offer type:RTCSdpTypeOffer];
    [_peerConnection setRemoteDescriptionWithSessionDescription:remoteSDP completionHandler:^(NSError * _Nullable error) {
        if (error) {
            NSLog(@"设置远程 Offer 失败: %@", error.localizedDescription);
            return;
        }
        
        // 创建 Answer
        [self createAnswer];
    }];
}

// 创建 Answer
- (void)createAnswer {
    RTCOfferAnswerConstraints *constraints = [[RTCOfferAnswerConstraints alloc] init];
    [_peerConnection createAnswerWithConstraints:constraints completionHandler:^(RTCSessionDescription * _Nullable sdp, NSError * _Nullable error) {
        if (error) {
            NSLog(@"创建 Answer 失败: %@", error.localizedDescription);
            return;
        }
        
        [self.peerConnection setLocalDescriptionWithSessionDescription:sdp completionHandler:^(NSError * _Nullable error) {
            if (error) {
                NSLog(@"设置本地 Answer 失败: %@", error.localizedDescription);
                return;
            }
            
            // 将 Answer 发送给信令服务器
            NSString *answerString = [self sessionDescriptionToString:sdp];
            NSLog(@"生成 Answer: %@", answerString);
            // [self.signalingClient sendAnswer:answerString];
        }];
    }];
}

// 处理远程 Answer
- (void)handleRemoteAnswer:(NSString *)answer {
    RTCSessionDescription *remoteSDP = [self stringToSessionDescription:answer type:RTCSdpTypeAnswer];
    [_peerConnection setRemoteDescriptionWithSessionDescription:remoteSDP completionHandler:^(NSError * _Nullable error) {
        if (error) {
            NSLog(@"设置远程 Answer 失败: %@", error.localizedDescription);
        }
    }];
}

// 处理远程 ICE 候选者
- (void)handleRemoteICECandidate:(NSString *)candidate {
    NSDictionary *candidateDict = [NSJSONSerialization JSONObjectWithData:[candidate dataUsingEncoding:NSUTF8StringEncoding] options:0 error:nil];
    if (!candidateDict) return;
    
    RTCIceCandidate *iceCandidate = [[RTCIceCandidate alloc] 
        initWithSdpMLineIndex:[candidateDict[@"sdpMLineIndex"] integerValue]
        sdpMid:candidateDict[@"sdpMid"]
        sdp:candidateDict[@"sdp"]];
    
    [_peerConnection addIceCandidate:iceCandidate completionHandler:^(NSError * _Nullable error) {
        if (error) {
            NSLog(@"添加远程 ICE 候选者失败: %@", error.localizedDescription);
        }
    }];
}

// 断开连接
- (void)disconnect {
    [_peerConnection close];
    _peerConnection = nil;
    [_localStream removeAllAudioTracks];
    [_localStream removeAllVideoTracks];
    _localStream = nil;
}

#pragma mark - RTCPeerConnectionDelegate

// 收到远程媒体流
- (void)peerConnection:(RTCPeerConnection *)peerConnection didAddStream:(RTCMediaStream *)stream {
    NSLog(@"收到远程媒体流");
    if ([self.delegate respondsToSelector:@selector(didReceiveRemoteStream:)] && stream) {
        [self.delegate didReceiveRemoteStream:stream];
    }
}

// 生成 ICE 候选者
- (void)peerConnection:(RTCPeerConnection *)peerConnection didGenerateIceCandidate:(RTCIceCandidate *)candidate {
    NSDictionary *candidateDict = @{
        @"sdpMLineIndex": @(candidate.sdpMLineIndex),
        @"sdpMid": candidate.sdpMid ?: @"",
        @"sdp": candidate.sdp
    };
    
    NSData *jsonData = [NSJSONSerialization dataWithJSONObject:candidateDict options:0 error:nil];
    NSString *candidateString = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];
    
    // 将 ICE 候选者发送给信令服务器
    NSLog(@"生成 ICE 候选者: %@", candidateString);
    // [self.signalingClient sendICECandidate:candidateString];
}

#pragma mark - 工具方法

// 媒体约束配置
- (RTCMediaConstraints *)defaultMediaConstraints {
    return [[RTCMediaConstraints alloc] initWithMandatoryConstraints:@[] optionalConstraints:@[]];
}

// 视频约束配置
- (RTCMediaConstraints *)videoConstraints {
    return [[RTCMediaConstraints alloc] initWithMandatoryConstraints:@[
        [[RTCPair alloc] initWithKey:@"maxWidth" value:@"1280"],
        [[RTCPair alloc] initWithKey:@"maxHeight" value:@"720"],
        [[RTCPair alloc] initWithKey:@"maxFrameRate" value:@"30"]
    ] optionalConstraints:@[]];
}

// 将 SessionDescription 转换为字符串
- (NSString *)sessionDescriptionToString:(RTCSessionDescription *)sdp {
    NSDictionary *dict = @{
        @"type": [self sdpTypeToString:sdp.type],
        @"sdp": sdp.sdp
    };
    NSData *jsonData = [NSJSONSerialization dataWithJSONObject:dict options:0 error:nil];
    return [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];
}

// 将字符串转换为 SessionDescription
- (RTCSessionDescription *)stringToSessionDescription:(NSString *)string type:(RTCSdpType)type {
    NSData *data = [string dataUsingEncoding:NSUTF8StringEncoding];
    NSDictionary *dict = [NSJSONSerialization JSONObjectWithData:data options:0 error:nil];
    return [[RTCSessionDescription alloc] initWithType:type sdp:dict[@"sdp"]];
}

// SDP 类型转换
- (NSString *)sdpTypeToString:(RTCSdpType)type {
    switch (type) {
        case RTCSdpTypeOffer: return @"offer";
        case RTCSdpTypeAnswer: return @"answer";
        case RTCSdpTypePrAnswer: return @"pranswer";
        case RTCSdpTypeRollback: return @"rollback";
        default: return @"";
    }
}

@end

调用OC：ViewController.m

objectivec 复制代码 
#import "ViewController.h"
#import <WebRTC/WebRTC.h>

@interface ViewController ()
@property (nonatomic, strong) WebRTCManager *rtcManager;
@property (nonatomic, strong) UIView *localVideoView;
@property (nonatomic, strong) UIView *remoteVideoView;
@property (nonatomic, strong) UIButton *connectButton;
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = UIColor.whiteColor;
    
    [self setupUI];
    [self setupWebRTC];
}

- (void)setupUI {
    // 本地视频视图
    _localVideoView = [[UIView alloc] init];
    _localVideoView.backgroundColor = UIColor.lightGrayColor;
    _localVideoView.translatesAutoresizingMaskIntoConstraints = NO;
    [self.view addSubview:_localVideoView];
    
    // 远程视频视图
    _remoteVideoView = [[UIView alloc] init];
    _remoteVideoView.backgroundColor = UIColor.darkGrayColor;
    _remoteVideoView.translatesAutoresizingMaskIntoConstraints = NO;
    [self.view addSubview:_remoteVideoView];
    
    // 连接按钮
    _connectButton = [UIButton buttonWithType:UIButtonTypeSystem];
    [_connectButton setTitle:@"建立连接" forState:UIControlStateNormal];
    [_connectButton addTarget:self action:@selector(connectButtonTapped) forControlEvents:UIControlEventTouchUpInside];
    _connectButton.translatesAutoresizingMaskIntoConstraints = NO;
    [self.view addSubview:_connectButton];
    
    // 布局
    [NSLayoutConstraint activateConstraints:@[
        // 本地视频（右上角小窗口）
        [_localVideoView topAnchor constraintEqualToAnchor:self.view.safeAreaLayoutGuide.topAnchor constant:20],
        [_localVideoView.trailingAnchor constraintEqualToAnchor:self.view.trailingAnchor constant:-20],
        [_localVideoView.widthAnchor constraintEqualToConstant:120],
        [_localVideoView.heightAnchor constraintEqualToConstant:180],
        
        // 远程视频（全屏）
        [_remoteVideoView.topAnchor constraintEqualToAnchor:self.view.safeAreaLayoutGuide.topAnchor],
        [_remoteVideoView.leadingAnchor constraintEqualToAnchor:self.view.leadingAnchor],
        [_remoteVideoView.trailingAnchor constraintEqualToAnchor:self.view.trailingAnchor],
        [_remoteVideoView.bottomAnchor constraintEqualToAnchor:self.connectButton.topAnchor constant:-20],
        
        // 连接按钮
        [_connectButton.bottomAnchor constraintEqualToAnchor:self.view.safeAreaLayoutGuide.bottomAnchor constant:-20],
        [_connectButton.centerXAnchor constraintEqualToAnchor:self.view.centerXAnchor],
        [_connectButton.widthAnchor constraintEqualToConstant:120],
        [_connectButton.heightAnchor constraintEqualToConstant:44]
    ]];
}

- (void)setupWebRTC {
    _rtcManager = [[WebRTCManager alloc] initWithDelegate:self];
    [_rtcManager setupLocalStreamWithVideoView:self.localVideoView];
}

- (void)connectButtonTapped {
    [_rtcManager createOffer];
}

#pragma mark - WebRTCManagerDelegate

// 处理收到的远程流
- (void)didReceiveRemoteStream:(RTCMediaStream *)stream {
    dispatch_async(dispatch_get_main_queue(), ^{
        // 渲染远程视频
        if (stream.videoTracks.count > 0) {
            RTCVideoTrack *remoteVideoTrack = stream.videoTracks[0];
            
            RTCMTLVideoView *rendererView = [[RTCMTLVideoView alloc] init];
            rendererView.frame = self.remoteVideoView.bounds;
            rendererView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
            [self.remoteVideoView addSubview:rendererView];
            
            [remoteVideoTrack addRenderer:[[RTCVideoRendererAdapter alloc] initWithRenderer:rendererView]];
        }
    });
}

- (void)dealloc {
    [_rtcManager disconnect];
}

@end

代码说明

这个示例实现了 iOS 平台上基于 WebRTC 的基本音视频推拉流功能，主要包含以下部分：
WebRTCManager：核心管理类，负责：

  • 初始化 WebRTC 相关组件
  • 处理本地音视频流的捕获和预览
  • 管理 PeerConnection 连接
  • 处理 SDP 交换和 ICE 候选者

ViewController：界面控制器，负责：

  • 创建本地和远程视频的预览视图
  • 处理用户交互（如建立连接）
  • 渲染远程视频流

三、使用说明

这个示例缺少信令服务器的实现，你需要自己搭建一个信令服务器

在实际使用中，需要将代码中注释掉的信令发送部分替换为实际的网络请求

代码中的 STUN 服务器使用了 Google 的公共服务器，生产环境中建议使用自己的 STUN/TURN 服务器

四、扩展建议

  • 添加错误处理和重连机制
  • 实现多人通话功能
  • 添加视频质量控制
  • 实现屏幕共享功能
  • 添加音频 /video 开关控制

这个示例仅仅提供了基础的推拉流框架，你可以根据实际需求进行扩展和优化。

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