message: Ensured back image updates dynamically
  Tested backImage in a setTimeout
diff: @@ -255,10 +255,11 @@ API_AVAILABLE(ios(13.0)){
  if ([image isEqual:_backImage]) {
  return;
  }
  - _backImage = image;
  if (self.backImageDidLoadBlock) {
  self.backImageDidLoadBlock();
  }
  + _backImage = image;
  + [self updateStyle];
  }
  }
  