.m

- (void)panningEndedWithTranslation:(CGPoint)translation velocity:(CGPoint)velocity
{
    self.panGestureRecognizer.enabled = NO;

    CGFloat screenHeight = [[UIScreen mainScreen] bounds].size.height;
    __weak ViewController *weakSelf = self;

    switch (self.playerState) {
        case PlayerStateThumbnail:
            if (translation.y <= -screenHeight / 3 || velocity.y <= -100)
            {
                self.playerViewAnimator.reversed = NO;
                [self.playerViewAnimator addCompletion:^(UIViewAnimatingPosition finalPosition) {
                    weakSelf.playerState = PlayerStateFullscreen;
                    weakSelf.panGestureRecognizer.enabled = YES;
                }];
            }
            else
            {
                self.playerViewAnimator.reversed = YES;
                [self.playerViewAnimator addCompletion:^(UIViewAnimatingPosition finalPosition) {
                    weakSelf.playerState = PlayerStateThumbnail;
                    weakSelf.panGestureRecognizer.enabled = YES;
                }];
            }
            break;
        case PlayerStateFullscreen:
            if (translation.y >= screenHeight / 3 || velocity.y >= 100)
            {
                self.playerViewAnimator.reversed = NO;
                [self.playerViewAnimator addCompletion:^(UIViewAnimatingPosition finalPosition) {
                    weakSelf.playerState = PlayerStateThumbnail;
                    weakSelf.panGestureRecognizer.enabled = YES;
                }];
            }
            else
            {
                self.playerViewAnimator.reversed = YES;
                [self.playerViewAnimator addCompletion:^(UIViewAnimatingPosition finalPosition) {
                    weakSelf.playerState = PlayerStateFullscreen;
                    weakSelf.panGestureRecognizer.enabled = YES;
                }];
            }
    }

    CGVector velocityVector = CGVectorMake(velocity.x / 100, velocity.y / 100);
    UISpringTimingParameters *springParameters = [[UISpringTimingParameters alloc] initWithDampingRatio:0.8 initialVelocity:velocityVector];

    [self.playerViewAnimator continueAnimationWithTimingParameters:springParameters durationFactor:1.0];
}