Bug Transition动画ViewControllers

Question

我有一个简单的交互式动画：与页面之间的iOS过渡相同。但是当转换完成或取消时，它有时会回到原来的位置，就像后面的效果一样。这是我的代码，你可以测试一下，看看我的意思。我该如何解决？此外，是否有更好的方法在ViewControllers之间进行交互式转换？ THX

NavigationControllerDelegate.m

#import "NavigationControllerDelegate.h"
#import "Animator.h"

@interface NavigationControllerDelegate ()

@property (weak, nonatomic) IBOutlet UINavigationController *navigationController;
@property (strong, nonatomic) Animator* animator;
@property (strong, nonatomic) UIPercentDrivenInteractiveTransition* interactionController;

@end

@implementation NavigationControllerDelegate

- (void)awakeFromNib
{
    UIPanGestureRecognizer* panRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(pan:)];
    [self.navigationController.view addGestureRecognizer:panRecognizer];

    self.animator = [Animator new];
}

- (void)pan:(UIPanGestureRecognizer*)recognizer
{
    UIView* view = self.navigationController.view;

    if (recognizer.state == UIGestureRecognizerStateBegan) {
        CGPoint location = [recognizer locationInView:view];
        if (location.x <  CGRectGetMidX(view.bounds) && self.navigationController.viewControllers.count > 1) { // left half
            self.interactionController = [UIPercentDrivenInteractiveTransition new];
            [self.navigationController popViewControllerAnimated:YES];
        }
    } else if (recognizer.state == UIGestureRecognizerStateChanged) {
        CGPoint translation = [recognizer translationInView:view];
        CGFloat d = fabs(translation.x / CGRectGetWidth(view.bounds));
        [self.interactionController updateInteractiveTransition:d];
    } else if (recognizer.state == UIGestureRecognizerStateEnded) {
        CGPoint translation = [recognizer translationInView:view];
        CGFloat d = (translation.x / CGRectGetWidth(view.bounds));
        if (d > 0.5) {
            [self.interactionController finishInteractiveTransition];
        } else {
            [self.interactionController cancelInteractiveTransition];
        }
        self.interactionController = nil;
    }
}

- (id<UIViewControllerAnimatedTransitioning>)navigationController:(UINavigationController *)navigationController animationControllerForOperation:(UINavigationControllerOperation)operation fromViewController:(UIViewController *)fromVC toViewController:(UIViewController *)toVC
{
    if (operation == UINavigationControllerOperationPop) {
        return self.animator;
    }
    return nil;
}

- (id<UIViewControllerInteractiveTransitioning>)navigationController:(UINavigationController *)navigationController interactionControllerForAnimationController:(id<UIViewControllerAnimatedTransitioning>)animationController
{
    return self.interactionController;
}




@end

Animator.m

#import "Animator.h"

@implementation Animator

- (NSTimeInterval)transitionDuration:(id <UIViewControllerContextTransitioning>)transitionContext
{
    return 1;
}

- (void)animateTransition:(id<UIViewControllerContextTransitioning>)transitionContext
{
    CGRect screenBounds = [[UIScreen mainScreen] bounds];
    UIViewController* toViewController = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
    UIViewController* fromViewController = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
    [[transitionContext containerView] addSubview:toViewController.view];
    toViewController.view.frame = CGRectMake(-screenBounds.size.width, 0, screenBounds.size.width, screenBounds.size.height);

    [UIView animateWithDuration:[self transitionDuration:transitionContext] animations:^{
        toViewController.view.frame = CGRectMake(0, 0, screenBounds.size.width, screenBounds.size.height);
        fromViewController.view.frame = CGRectMake(screenBounds.size.width, 0, screenBounds.size.width, screenBounds.size.height);
    } completion:^(BOOL finished) {
        [transitionContext completeTransition:![transitionContext transitionWasCancelled]];

    }];
}


@end