iOS錄屏架構ReplayKit的應用總結

ReplayKit是iOS自帶的一個螢幕錄制的架構，其支援應用程式對目前應用内頁面進行錄屏，并将最終的視訊儲存到系統相冊中。ReplayKit在iOS 9之後引入，其接口簡介，可以非常友善的為應用添加錄屏功能。需要注意，在某些iOS 12系統上，開啟錄屏可能會失敗(通常需要重新開機裝置解決)。

在ReplayKit架構中，有兩個非常重要的類，分别是RPScreenRecorder類與RPPreviewViewController類。RPScreenRecorder是錄屏核心功能類，RPPreviewViewController是錄屏結束後的預覽控制器類。

  下面，列舉了一個簡單的錄屏示例代碼：
           

@interface ViewController () <RPScreenRecorderDelegate, RPPreviewViewControllerDelegate>

@end

@implementation ViewController

• (void)viewDidLoad {

  self.view.backgroundColor = [UIColor whiteColor];

  [super viewDidLoad];

  // 擷取錄屏功能是否可用

  NSLog(@"%d", [RPScreenRecorder sharedRecorder].available);

  // 設定錄屏代理

  [RPScreenRecorder sharedRecorder].delegate = self;

  UIButton *btn = [UIButton buttonWithType:UIButtonTypeSystem];

  [btn setTitle:@"Start" forState:UIControlStateNormal];

  [btn addTarget:self action:@selector(start) forControlEvents:UIControlEventTouchUpInside];

  btn.frame = CGRectMake(100, 100, 100, 30);

  [self.view addSubview:btn];

  UIButton *btn2 = [UIButton buttonWithType:UIButtonTypeSystem];

  [btn2 setTitle:@"End" forState:UIControlStateNormal];

  [btn2 addTarget:self action:@selector(stop) forControlEvents:UIControlEventTouchUpInside];

  btn2.frame = CGRectMake(100, 150, 100, 30);

  [self.view addSubview:btn2];

}

• (void)stop {

  // 結束錄屏

  [[RPScreenRecorder sharedRecorder] stopRecordingWithHandler:^(RPPreviewViewController _Nullable previewViewController, NSError _Nullable error) {

  NSLog(@"stopRecordingWithHandler");
  if (!error) {
      previewViewController.previewControllerDelegate = self;
      // 到視訊預覽控制器
      [self presentViewController:previewViewController animated:YES completion:nil];
  }           

  }];

// 開始錄屏

• (void)start {

  [[RPScreenRecorder sharedRecorder] startRecordingWithHandler:^(NSError * _Nullable error) {

  NSLog(@"startRecordingWithHandlerError:%@", error);           

• (void)touchesBegan:(NSSet)touches withEvent:(UIEvent )event {

  self.view.backgroundColor = [UIColor colorWithRed:arc4random()%255/255.0 green:arc4random()%255/255.0 blue:arc4random()%255/255.0 alpha:1];

// 錄屏結束的回調

• (void)screenRecorder:(RPScreenRecorder )screenRecorder didStopRecordingWithPreviewViewController:(nullable RPPreviewViewController )previewViewController error:(nullable NSError *)error {

  NSLog(@"didStopRecordingWithPreviewViewControllerError:%@", error);

// 錄屏可用性改變的回調

• (void)screenRecorderDidChangeAvailability:(RPScreenRecorder *)screenRecorder {

  NSLog(@"screenRecorderDidChangeAvailability:%d", screenRecorder.available);

// 錄屏預覽控制器的代理回調

• (void)previewControllerDidFinish:(RPPreviewViewController *)previewController {

  [previewController dismissViewControllerAnimated:YES completion:nil];

• (void)previewController:(RPPreviewViewController )previewController didFinishWithActivityTypes:(NSSet )activityTypes {

  NSLog(@"didFinishWithActivityTypes %@", activityTypes);

其中，RPScreenRecorder類中提供了豐富的接口可以使用，列舉如下：

@interface RPScreenRecorder : NSObject

// 擷取單例

• (RPScreenRecorder *)sharedRecorder;

// iOS 10 之前使用，可以通知是否開啟麥克風

• (void)startRecordingWithMicrophoneEnabled:(BOOL)microphoneEnabled handler:(nullable void(^)(NSError * _Nullable error))handler;

// iOS 10 之後使用 開啟錄屏

• (void)startRecordingWithHandler:(nullable void(^)(NSError * _Nullable error))handler;

// 結束錄屏

• (void)stopRecordingWithHandler:(nullable void(^)(RPPreviewViewController _Nullable previewViewController, NSError _Nullable error))handler;

// 放棄錄屏

• (void)discardRecordingWithHandler:(void(^)(void))handler;

// 開啟錄屏，可以擷取到視訊流資料 iOS 11後可用

• (void)startCaptureWithHandler:(nullable void(^)(CMSampleBufferRef sampleBuffer, RPSampleBufferType bufferType, NSError _Nullable error))captureHandler completionHandler:(nullable void(^)(NSError _Nullable error))completionHandler;

// 結束視訊流捕獲

• (void)stopCaptureWithHandler:(nullable void(^)(NSError * _Nullable error))handler;

// 設定代理對象

@property (nonatomic, weak, nullable) id delegate;

// 錄屏功能是否可用

@property (nonatomic, readonly, getter=isAvailable) BOOL available;

// 是否正在錄制中

@property (nonatomic, readonly, getter=isRecording) BOOL recording;

// 是否使用麥克風

@property (nonatomic, getter=isMicrophoneEnabled) BOOL microphoneEnabled;

// 是否可以使用相機

@property (nonatomic, getter=isCameraEnabled) BOOL cameraEnabled;

// 設定攝像頭模式 前置/後置

@property (nonatomic) RPCameraPosition cameraPosition;

// 相機預覽視圖

@property (nonatomic, readonly, nullable) UIView *cameraPreviewView;

在錄屏的時候，也支援調用系統的麥克風和攝像頭共同完成錄制。RPScreenRecorderDelegate協定中定義了一些回調方法，如下：

// 停止錄屏後的回調 iOS 10 之前使用

• (void)screenRecorder:(RPScreenRecorder )screenRecorder didStopRecordingWithError:(NSError )error previewViewController:(nullable RPPreviewViewController *)previewViewController;

// 停止錄屏後的回調 iOS 10 之後使用

• (void)screenRecorder:(RPScreenRecorder )screenRecorder didStopRecordingWithPreviewViewController:(nullable RPPreviewViewController )previewViewController error:(nullable NSError *)error;

// 錄屏權限更改的回調

• (void)screenRecorderDidChangeAvailability:(RPScreenRecorder *)screenRecorder;

RPPreviewViewController類是視訊預覽控制器類，這個控制器沒有暴露太多的屬性給開發者使用，其中預覽模式可以選擇分享模式或編輯模式，除此之外，其中還提供了一個代理協定給開發者進行使用，用來對使用者的操作進行處理，如下：

@protocol RPPreviewViewControllerDelegate

@optional

// 預覽結束

• (void)previewControllerDidFinish:(RPPreviewViewController *)previewController;

// 使用者行為回調

• (void)previewController:(RPPreviewViewController )previewController didFinishWithActivityTypes:(NSSet )activityTypes;