iOS 7自定义过渡故障

此视频显示了我遇到的问题.
http://www.youtube.com/watch?v=C9od_2KZAbs

我正在尝试使用UIPanGestureRecognizer创建自定义推送交互式转换.我有一个交互式转换委托(使用UIPercentDrivenInteractiveTransition)和一个过渡动画师.

以下是平移手势控制转换的方式：

- (void) panGestureRecognized:(UIPanGestureRecognizer *) gestureRecogznier {

    CGPoint translation = [gestureRecogznier translationInView:gestureRecogznier.view];

    if (gestureRecogznier.state == UIGestureRecognizerStateBegan) {

        self.interactiveTransitionAnimator = [[UIPercentDrivenInteractiveTransition alloc] init];

        EVDetailViewController *detailViewController = [self.storyboard instantiateViewControllerWithIdentifier:@"EVDetailViewController"];
        [self.navigationController pushViewController:detailViewController animated:YES];
    }
    else if (gestureRecogznier.state == UIGestureRecognizerStateChanged) {

        CGFloat d = (translation.x / CGRectGetWidth(self.view.bounds)) * -1;
        [self.interactiveTransitionAnimator updateInteractiveTransition:d];
    }
    else if (gestureRecogznier.state == UIGestureRecognizerStateEnded) {

        if ([gestureRecogznier velocityInView:self.view].x < 0) {
            [self.interactiveTransitionAnimator finishInteractiveTransition];
        } else {
            [self.interactiveTransitionAnimator cancelInteractiveTransition];
        }

        self.interactiveTransitionAnimator = nil;
    }
}

UINavigationControllerDelegate处理两个转换委托对象的自动售货,这是在调用pushViewController：时触发的.

过渡动画师有一个非常简单的动画：

- (void)animateTransition:(id<UIViewControllerContextTransitioning>)transitionContext {

    UIViewController* toViewController = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
    [[transitionContext containerView] addSubview:toViewController.view];

    CGRect finalToVCFrame = [transitionContext finalFrameForViewController:toViewController];

    if (self.operation == UINavigationControllerOperationPush) {

        // set offscreen to the right
        toViewController.view.frame = CGRectMake(320.0f,0.0f,320.0f,568.0f);

        [UIView animateWithDuration:[self transitionDuration:transitionContext] delay:0.0f options:0 animations:^{

            toViewController.view.frame = finalToVCFrame;

        } completion:^(BOOL finished) {

            // *** When this is called,the glitch occurs
            [transitionContext completeTransition:YES];
        }];
    }
}

在视频中,平移手势结束大约60％的通过,这触发了finishInteractiveTransition调用.一切顺利,直到UIView基于块的动画中的完成块调用completeTransition：.调用此方法时,toViewController将不必要地重新设置推送动画的最后一部分.在视频中,红色视图是窗口.动画持续时间为3秒.

我无法弄清楚为什么会这样.它看起来像手势结束时和动作完成传递之间的动画发生两次.有任何想法吗？

self.interactiveTransitionAnimator.completionSpeed = 0.999;