gistfile1.m

- (void)setupSetVideoListener
{
  BCFlowChain *chain = [BCFlowChain chain];
  setVideoListener = [emitter on:BCEventSetVideo callBlock:^(BCEvent *setVideoEvent){
    [chain reset];
    [chain abortOn:BCEventSetVideo];
    [chain emit:BCEventShouldSetVideo];
    [chain thenDo:^(BCEvent *shouldSetVideoEvent){
      if (shouldSetVideoEvent.defaultPrevented) {
        [chain emit:BCEventCancelledSetVideo parentEvent:setVideoEvent];
        [chain thenAbort];
      }
    }];
    [chain emit:BCEventWillSetVideo parentEvent:setVideoEvent];
    [chain emit:BCEventSetRendition withDetails:
      [NSDictionary dictionaryWithObject:rendition forKey:@"rendition"]];
    [chain emit:BCEventSetVideoStill withDetails:
      [NSDictionary dictionaryWithObject:videoStill forKey:@"videoStill"]];
    [chain waitForBoth:BCEventDidSetRendition and:BCEventDidSetVideoStill];
    [chain thenDo:^{
      self.video = [setVideoEvent.details objectForKey:@"video"];
      [chain emit:BCEventDidSetVideo parentEvent:setVideoEvent];
    }];
  }];
}