animateLockWithGesture.m

- (void)animateLockWithGestureRecognizer:(UIPanGestureRecognizer *)gr completion:(void (^)(void))completionBlock {
  [self removeGestureRecognizer:gr];

  //calculate animationDuration based on gr position and velocity

  [UIView animateWithDuration:animationDuration animations:^{
    //some calculation logic to determine a view’s location

    [self updateSliderColor:offset];
  } completion:^(BOOL finished) {
    if (completionBlock) {
      completionBlock();
    }
  }];
}