Objectivec 使用 UIViewControllerInteractiveTransitioning 委托协议实现自定义 UIViewController 交互式过渡的正确方法

1)将手势与UIViewControllerInteractiveTransitioning对象绑定的最简单方法是将其设为UIPercentDrivenInteractiveTransition的子类.然后，在实现手势处理程序的地方，这里调用updateInteractiveTransition:，并给出代码示例:

-(void)handlePinch:(UIPinchGestureRecognizer *)pinch {

    CGFloat scale = pinch.scale;
    switch (pinch.state) {
      case UIGestureRecognizerStateBegan: {
          _startScale = scale;
          self.interactive = YES;
          [self.navigationController popViewControllerAnimated:YES];
          break;
      }
      case UIGestureRecognizerStateChanged: {
          CGFloat percent = (1.0 - scale/_startScale);
          [self updateInteractiveTransition:(percent < 0.0) ? 0.0 : percent];
          break;
      }
      case UIGestureRecognizerStateEnded: {
          CGFloat percent = (1.0 - scale/_startScale);
          BOOL cancelled = ([pinch velocity] < 5.0 && percent <= 0.3);
          if (cancelled) [self cancelInteractiveTransition];
          else [self finishInteractiveTransition];
          break;
      }
      case UIGestureRecognizerStateCancelled: {
          CGFloat percent = (1.0 - scale/_startScale);
          BOOL cancelled = ([pinch velocity] < 5.0 && percent <= 0.3);
          if (cancelled) [self cancelInteractiveTransition];
          else [self finishInteractiveTransition];
          break;
      }
    }
}

这个代码来自https://www.captechconsulting.com/blogs/ios-7-tutorial-series-custom-navigation-transitions--more

2) UIViewControllerAnimatedTransitioning的功能animateTransition用于执行交互转换.由于您之前拨打updateInteractiveTransition，它会自动在"关键帧"中进行分区.但是我想，如果你实现了UIViewControllerInteractiveTransitioning的startInteractiveTransition:方法(因此不使用UIPercentDrivenInteractiveTransition子类)，那么你就有责任管理完全的转换(不确定这一点……抱歉，我认为文档不是很清楚).