iOS 屏幕实时共享功能实践(内附详细代码)
很多人对屏幕共享的印象还只停留在 PC 端做 PPT 汇报的场景中,但事实上,今天的屏幕共享早已跨界出圈了。比如一个大家很熟悉的场景 —— 游戏直播,主播就需要将自己的画面以“屏幕共享”的形式展示给观众,并且对实时性、流畅性的要求非常高。
对于很多手游主播来说,目前比较常见的做法是,通过借助 PC 端的中转将手机游戏画面进行直播分享;而实际上,通过调用融云屏幕共享 SDK,直接在手机端就可以拥有屏幕实时共享的能力。
本文就将主要围绕 iOS 屏幕共享问题展开讨论,一起了解 iOS ReplayKit 框架的发展过程,各个阶段的功能演变,以及结合融云屏幕共享 SDK 实现相应功能的代码和思路。
01 ReplayKit 发展史
iOS 端屏幕录制 ReplayKit 是从 iOS9 开始出现的。
iOS9
WWDC15 初次提供 ReplayKit 框架,它的初期出现主要用于录制视频,存于相册。
iOS9 开始录制和停止录制两个 API 有很大的局限性:
只能获取系统生成好的 MP4 文件,且不能直接获取,需要先保存到相册,再从相册获取;
不可以获取源数据,也就是 pcm 和 yuv 数据;
给开发者的权限低,不能录制其他 APP,且退出后台就不会录制了,只能录制当前 APP 画面。
可控行为在于:
停止录制可弹出一个视频预览窗口,能进行保存或取消或分享该视频文件;
录制完成后可以进行查看、编辑,或者通过指定方式分享。
开始录制视频的 API 如下所示。
/*!
Deprecated. Use startRecordingWithHandler: instead. @abstract Starts app recording with a completion handler. Note that before recording actually starts, the user may be prompted with UI to confirm recording.
@param microphoneEnabled Determines whether the microphone input should be included in the recorded movie audio.
@discussion handler Called after user interactions are complete. Will be passed an optional NSError in the RPRecordingErrorDomain domain if there was an issue starting the recording.
*/
[[RPScreenRecorder sharedRecorder] startRecordingWithMicrophoneEnabled:YES handler:^(NSError * _Nullable error) {
if (error) {
//TODO.....
}
}];
调用开始录屏的时候,系统会弹出一个弹窗,需要用户进行确认后才能正常录制。
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停止录制视频的 API 如下所示。
/*! @abstract Stops app recording with a completion handler.
@discussion handler Called when the movie is ready. Will return an instance of RPPreviewViewController on success which should be presented using [UIViewController presentViewController:animated:completion:]. Will be passed an optional NSError in the RPRecordingErrorDomain domain if there was an issue stopping the recording.
*/
[[RPScreenRecorder sharedRecorder] stopRecordingWithHandler:^(RPPreviewViewController *previewViewController, NSError *error){
[self presentViewController:previewViewController animated:YES completion:^{
//TODO.....
}];
}];
iOS10
经过 WWDC16 发布,苹果对 ReplayKit 进行了升级,开放了源数据获取途径,增加了两个 Extension 的 Target。具体情况包括:
新增 UI 和 Upload 两个 Extension 的 Target;
增加开发者权限,允许用户登录到服务并设立了直播、源数据的操作;
只能通过扩展区录制屏幕,不仅可以录制自己的 APP,还可以录制其他 APP;
只能录制 APP 屏幕,不能录制 iOS 系统屏幕。
创建 Extension 的方法如下图所示。
文章图片
UI Extension
/*
这俩API可以理解为弹窗触发的事件回调函数;
*/
- (void)userDidFinishSetup {
//触发Host App 的RPBroadcastActivityViewControllerDelegate
}- (void)userDidCancelSetup {
//触发Host App 的RPBroadcastActivityViewControllerDelegate
}
Upload Extension
- (void)broadcastStartedWithSetupInfo:(NSDictionary *)setupInfo {
// User has requested to start the broadcast. Setup info from the UI extension can be supplied but optional.
//这里主要就是做一些初始化的行为操作
}- (void)broadcastPaused {
// User has requested to pause the broadcast. Samples will stop being delivered.
//接收系统暂停信号
}- (void)broadcastResumed {
// User has requested to resume the broadcast. Samples delivery will resume.
//接收系统恢复信号
}- (void)broadcastFinished {
// User has requested to finish the broadcast.
//接收系统完成信号
} //这里就是此次更新最炸的点,我们可以拿到系统源数据,而且系统还分了三类,分别为视频帧、App内声音、麦克风
- (void)processSampleBuffer:(CMSampleBufferRef)sampleBuffer withType:(RPSampleBufferType)sampleBufferType {switch (sampleBufferType) {
case RPSampleBufferTypeVideo:
// Handle video sample buffer
break;
case RPSampleBufferTypeAudioApp:
// Handle audio sample buffer for app audio
break;
case RPSampleBufferTypeAudioMic:
// Handle audio sample buffer for mic audio
break;
default:
break;
}
}
Host APP
RPBroadcastControllerDelegate
//start
if (![RPScreenRecorder sharedRecorder].isRecording) {
[RPBroadcastActivityViewController loadBroadcastActivityViewControllerWithHandler:^(RPBroadcastActivityViewController * _Nullable broadcastActivityViewController, NSError * _Nullable error) {
if (error) {
NSLog(@"RPBroadcast err %@", [error localizedDescription]);
}
broadcastActivityViewController.delegate = self;
/*RPBroadcastActivityViewControllerDelegate*/
[self presentViewController:broadcastActivityViewController animated:YES completion:nil];
}];
}#pragma mark- RPBroadcastActivityViewControllerDelegate
- (void)broadcastActivityViewController:(RPBroadcastActivityViewController *)broadcastActivityViewController didFinishWithBroadcastController:(RPBroadcastController *)broadcastController error:(NSError *)error {
if (error) {
//TODO:
NSLog(@"broadcastActivityViewController:%@",error.localizedDescription);
return;
}[broadcastController startBroadcastWithHandler:^(NSError * _Nullable error) {
if (!error) {
NSLog(@"success");
} else {
NSLog(@"startBroadcast:%@",error.localizedDescription);
}
}];
}#pragma mark- RPBroadcastControllerDelegate
- (void)broadcastController:(RPBroadcastController *)broadcastController didFinishWithError:(nullable NSError *)error{
NSLog(@"didFinishWithError: %@", error);
}
- (void)broadcastController:(RPBroadcastController *)broadcastController didUpdateServiceInfo:(NSDictionary *> *)serviceInf {
NSLog(@"didUpdateServiceInfo: %@", serviceInf);
}
【iOS 屏幕实时共享功能实践(内附详细代码)】iOS11
经过 WWDC17,苹果对 ReplayKit2 进行了再次升级,新增了 APP 外数据获取,可以直接在 Host App 中获取,具体包括:
可以直接在 Host APP 中处理录制的 APP 屏幕数据;
可以录制 iOS 系统的屏幕数据,但是需要通过控制中心手动开启。
启动 APP 屏幕录制
[[RPScreenRecorder sharedRecorder] startCaptureWithHandler:^(CMSampleBufferRef_Nonnull sampleBuffer, RPSampleBufferType bufferType, NSError * _Nullable error) {
[self.videoOutputStream write:sampleBuffer error:nil];
} completionHandler:^(NSError * _Nullable error) {
NSLog(@"startCaptureWithHandler:%@",error.localizedDescription);
}];
停止 APP 屏幕录制
[[RPScreenRecorder sharedRecorder] stopCaptureWithHandler:^(NSError * _Nullable error) {
[self.assetWriter finishWritingWithCompletionHandler:^{
//TODO
}];
}];
iOS12
苹果在 WWDC18 上针对 ReplayKit 更新,新增了 RPSystemBroadcastPickerView,类用于在 APP 内可启动系统录制,极大地简化了屏幕录制的流程。
if (@available(iOS 12.0, *)) {
self.systemBroadcastPickerView = [[RPSystemBroadcastPickerView alloc] initWithFrame:CGRectMake(0, 0, 50, 80)];
self.systemBroadcastPickerView.preferredExtension = ScreenShareBuildID;
self.systemBroadcastPickerView.showsMicrophoneButton = NO;
self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithCustomView:self.systemBroadcastPickerView];
} else {
// Fallback on earlier versions
}
02 融云 RongRTCReplayKitExt
为减轻开发者的集成负担,融云专门打造了 RongRTCReplayKitExt 库,以服务于屏幕共享业务。
设计思路
Upload Extension
SampleHandler 进行数据的接收、RCRTCReplayKitEngine 初始化配置 ;
RCRTCReplayKitEngine 初始化 socket 通讯、处理YUV数据转i420、控制内存峰值。
App
原有发布流程:
IM 连接--加入房间--发布资源(RCRTCScreenShareOutputStream);
内部做 socket 初始化、实现协议接收处理过的数据、推流。
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代码示例
Upload extension
#import "SampleHandler.h"
#import static NSString *const ScreenShareGroupID = @"group.cn.rongcloud.rtcquickdemo.screenshare";
@interface SampleHandler ()
@end@implementation SampleHandler- (void)broadcastStartedWithSetupInfo:(NSDictionary *)setupInfo {
// User has requested to start the broadcast. Setup info from the UI extension can be supplied but optional.
[[RCRTCReplayKitEngine sharedInstance] setupWithAppGroup:ScreenShareGroupID delegate:self];
}- (void)broadcastPaused {
// User has requested to pause the broadcast. Samples will stop being delivered.
}- (void)broadcastResumed {
// User has requested to resume the broadcast. Samples delivery will resume.
}- (void)broadcastFinished {
[[RCRTCReplayKitEngine sharedInstance] broadcastFinished];
}- (void)processSampleBuffer:(CMSampleBufferRef)sampleBuffer withType:(RPSampleBufferType)sampleBufferTypeAPI_AVAILABLE(ios(10.0)) {
switch (sampleBufferType) {
case RPSampleBufferTypeVideo:
[[RCRTCReplayKitEngine sharedInstance] sendSampleBuffer:sampleBuffer withType:RPSampleBufferTypeVideo];
break;
case RPSampleBufferTypeAudioApp:
// Handle audio sample buffer for app audio
break;
case RPSampleBufferTypeAudioMic:
// Handle audio sample buffer for mic audio
break;
default:
break;
}
}#pragma mark - RongRTCReplayKitExtDelegate
-(void)broadcastFinished:(RCRTCReplayKitEngine *)broadcast reason:(RongRTCReplayKitExtReason)reason {
NSString *tip = @"";
switch (reason) {
case RongRTCReplayKitExtReasonRequestedByMain:
tip = @"屏幕共享已结束......";
break;
case RongRTCReplayKitExtReasonDisconnected:
tip = @"应用断开.....";
break;
case RongRTCReplayKitExtReasonVersionMismatch:
tip = @"集成错误(SDK 版本号不相符合)........";
break;
}NSError *error = [NSError errorWithDomain:NSStringFromClass(self.class)
code:0
userInfo:@{
NSLocalizedFailureReasonErrorKey:tip
}];
[self finishBroadcastWithError:error];
}
Host App
- (void)joinRoom {
RCRTCVideoStreamConfig *videoConfig = [[RCRTCVideoStreamConfig alloc] init];
videoConfig.videoSizePreset = RCRTCVideoSizePreset720x480;
videoConfig.videoFps = RCRTCVideoFPS30;
[[RCRTCEngine sharedInstance].defaultVideoStream setVideoConfig:videoConfig];
RCRTCRoomConfig *config = [[RCRTCRoomConfig alloc] init];
config.roomType = RCRTCRoomTypeNormal;
[self.engine enableSpeaker:YES];
__weak typeof(self) weakSelf = self;
[self.engine joinRoom:self.roomId
config:config
completion:^(RCRTCRoom *_Nullable room, RCRTCCode code) {
__strong typeof(weakSelf) strongSelf = weakSelf;
if (code == RCRTCCodeSuccess) {
self.room = room;
room.delegate = self;
[self publishScreenStream];
} else {
[UIAlertController alertWithString:@"加入房间失败" inCurrentViewController:strongSelf];
}
}];
}- (void)publishScreenStream {
self.videoOutputStream = [[RCRTCScreenShareOutputStream alloc] initWithAppGroup:ScreenShareGroupID];
RCRTCVideoStreamConfig *videoConfig = self.videoOutputStream.videoConfig;
videoConfig.videoSizePreset = RCRTCVideoSizePreset1280x720;
videoConfig.videoFps = RCRTCVideoFPS24;
[self.videoOutputStream setVideoConfig:videoConfig];
[self.room.localUser publishStream:self.videoOutputStream
completion:^(BOOL isSuccess, RCRTCCode desc) {
if (isSuccess) {
NSLog(@"发布自定义流成功");
} else {
NSLog(@"发布自定义流失败%@", [NSString stringWithFormat:@"订阅远端流失败:%ld", (long) desc]);
}
}];
}
03 一些注意事项
第一,ReplayKit2 内存不能超过 50MB,一旦超过峰值系统会进行强制回收,所以在 Extension 里面处理数据需要格外注意内存释放。
第二,进程之前通讯,如果是以 CFDefaultcenter 不能携带参数,只能发送消息;如果需要携带参数,必须做本地文件缓存。这里需要注意的一个问题是,在 debug 模式下运行可以打印出数据,在 release 下获取不到本地文件数据,具体实现可参见 Github 中的攻略。
最后想小小吐槽一下:非正常结束录屏时,系统往往会出现弹窗,且这个弹窗无法删除,只能重启设备 —— 这应该算是 iOS 系统一个比较恼人的 BUG 了。
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