ベストプラクティス

input.type = FBFrameTypeVideo;
FBImageFrame *output = [engine processImage:input];

preview.type = FBFrameTypeImage;
FBImageFrame *previewOut = [engine processImage:preview];

full.type = FBFrameTypeImage;
FBImageFrame *exportOut = [engine processImage:full];

[engine setSmoothing:0.25f];
[engine setSmoothingStyle:FBSmoothingStyle_Natural];
[engine setWhitening:0.15f];
[engine setReshape:FBReshape_FaceThin intensity:0.12f];
[engine setBeautySkinOnly:YES];

@interface BeautyEngineManager : NSObject
@property (nonatomic, strong, readonly) FBBeautyEffectEngine *engine;
@property (nonatomic, strong, readonly) dispatch_queue_t queue;
+ (instancetype)sharedManager;
@end

@implementation BeautyEngineManager

+ (instancetype)sharedManager {
  static BeautyEngineManager *instance;
  static dispatch_once_t onceToken;
  dispatch_once(&onceToken, ^{
    instance = [[BeautyEngineManager alloc] init];
  });
  return instance;
}

- (instancetype)init {
  self = [super init];
  if (self) {
    _queue = dispatch_queue_create("com.facebetter.process", DISPATCH_QUEUE_SERIAL);
    FBEngineConfig *config = [[FBEngineConfig alloc] init];
    config.appId = @"your_app_id";
    config.appKey = @"your_app_key";
    _engine = [FBBeautyEffectEngine createEngineWithConfig:config];
  }
  return self;
}

- (void)process:(FBImageFrame *)input completion:(void (^)(FBImageFrame * _Nullable))completion {
  dispatch_async(self.queue, ^{
    input.type = FBFrameTypeVideo;
    FBImageFrame *output = [self.engine processImage:input];
    dispatch_async(dispatch_get_main_queue(), ^{
      completion(output);
    });
  });
}

@end

FBEngineStats *stats = [engine getStats];
NSLog(@"fps=%.1f avg=%.2fms session=%.1fs",
      stats.fps, stats.avgProcessTimeMs, stats.sessionTimeS);

- (void)viewWillDisappear {
  [super viewWillDisappear];
  [self.captureSession stopRunning];
}

- (void)dealloc {
  self.beautyEffectEngine = nil;
}