4

我在 UINavigationController 中嵌入了几个视图控制器（一些模式，一些推送），并使用滑动手势在它们中导航：

// Gesture recognizers
UISwipeGestureRecognizer *downGesture = [[UISwipeGestureRecognizer alloc]initWithTarget:self action:@selector(dismissButton)];
downGesture.direction = UISwipeGestureRecognizerDirectionDown;
[downGesture setCancelsTouchesInView:NO];
[self.view addGestureRecognizer:downGesture];

这很好用，但是我希望用户能够以物理方式拖动模态呈现的视图控制器，例如，向下和离开屏幕，而不是只用轻弹和动画完成其余的工作，或者直接在屏幕上拖动并捕捉到上一个视图，而不是点击后退按钮。

我已经尝试在视图上使用平移手势来实现这一点，但当然前面的视图控制器在它后面是不可见的，它需要是。这个效果是如何正确实现的？使用视图控制器包含？如果是这样，当将一些视图控制器推入堆栈时，这将如何工作？我正在谈论的导航类型的示例可以在 LetterPress 应用程序中找到。

谢谢。

4

1 回答 1

9

是的，自定义容器视图是要走的路（iOS 5 及更高版本）。您基本上编写自己的自定义容器，使用内置childViewControllers属性来跟踪所有子视图控制器。您可能希望自己的财产，例如currentChildIndex，跟踪您当前使用的子控制器：

@property (nonatomic) NSInteger currentChildIndex;

您的父控制器可能应该有一些用于非滑动相关导航的推送和弹出方法，例如：

- (void)pushChildViewController:(UIViewController *)newChildController
{
    // remove any other children that we've popped off, but are still lingering about

    for (NSInteger index = [self.childViewControllers count] - 1; index > self.currentChildIndex; index--)
    {
        UIViewController *childController = self.childViewControllers[index];
        [childController willMoveToParentViewController:nil];
        [childController.view removeFromSuperview];
        [childController removeFromParentViewController];
    }

    // get reference to the current child controller

    UIViewController *currentChildController = self.childViewControllers[self.currentChildIndex];

    // set new child to be off to the right

    CGRect frame = self.containerView.bounds;
    frame.origin.x += frame.size.width;
    newChildController.view.frame = frame;

    // add the new child

    [self addChildViewController:newChildController];
    [self.containerView addSubview:newChildController.view];
    [newChildController didMoveToParentViewController:self];

    [UIView animateWithDuration:0.5
                     animations:^{
                         CGRect frame = self.containerView.bounds;
                         newChildController.view.frame = frame;
                         frame.origin.x -= frame.size.width;
                         currentChildController.view.frame = frame;
                     }];

    self.currentChildIndex++;
}

- (void)popChildViewController
{
    if (self.currentChildIndex == 0)
        return;

    UIViewController *currentChildController = self.childViewControllers[self.currentChildIndex];
    self.currentChildIndex--;
    UIViewController *previousChildController = self.childViewControllers[self.currentChildIndex];

    CGRect onScreenFrame = self.containerView.bounds;

    CGRect offToTheRightFrame = self.containerView.bounds;
    offToTheRightFrame.origin.x += offToTheRightFrame.size.width;

    [UIView animateWithDuration:0.5
                     animations:^{
                         currentChildController.view.frame = offToTheRightFrame;
                         previousChildController.view.frame = onScreenFrame;
                     }];
}

就个人而言，我为这两种方法定义了一个协议，并确保我的父控制器配置为符合该协议：

@protocol ParentControllerDelegate <NSObject>

- (void)pushChildViewController:(UIViewController *)newChildController;
- (void)popChildViewController;

@end

@interface ParentViewController : UIViewController <ParentControllerDelegate>
...
@end

然后，当一个孩子想推一个新的孩子时，它可以这样做：

ChildViewController *controller = ... // instantiate and configure your next controller however you want to do that

id<ParentControllerDelegate> parent = (id)self.parentViewController;
NSAssert([parent conformsToProtocol:@protocol(ParentControllerDelegate)], @"Parent must conform to ParentControllerDelegate");

[parent pushChildViewController:controller];

当一个孩子想要自己弹出时，它可以这样做：

id<ParentControllerDelegate> parent = (id)self.parentViewController;
NSAssert([parent conformsToProtocol:@protocol(ParentControllerDelegate)], @"Parent must conform to ParentControllerDelegate");

[parent popChildViewController];

然后父视图控制器设置了平移手势，以处理用户从一个孩子平移到另一个孩子：

- (void)handlePan:(UIPanGestureRecognizer *)gesture
{
    static UIView *currentView;
    static UIView *previousView;
    static UIView *nextView;

    if (gesture.state == UIGestureRecognizerStateBegan)
    {
        // identify previous view (if any)

        if (self.currentChildIndex > 0)
        {
            UIViewController *previous = self.childViewControllers[self.currentChildIndex - 1];
            previousView = previous.view;
        }
        else
        {
            previousView = nil;
        }

        // identify next view (if any)

        if (self.currentChildIndex < ([self.childViewControllers count] - 1))
        {
            UIViewController *next = self.childViewControllers[self.currentChildIndex + 1];
            nextView = next.view;
        }
        else
        {
            nextView = nil;
        }

        // identify current view

        UIViewController *current = self.childViewControllers[self.currentChildIndex];
        currentView = current.view;
    }

    // if we're in the middle of a pan, let's adjust the center of the views accordingly

    CGPoint translation = [gesture translationInView:gesture.view.superview];

    previousView.transform = CGAffineTransformMakeTranslation(translation.x, 0.0);
    currentView.transform = CGAffineTransformMakeTranslation(translation.x, 0.0);
    nextView.transform = CGAffineTransformMakeTranslation(translation.x, 0.0);

    // if we're all done, let's animate the completion (or if we didn't move far enough,
    // the reversal) of the pan gesture

    if (gesture.state == UIGestureRecognizerStateEnded ||
        gesture.state == UIGestureRecognizerStateCancelled ||
        gesture.state == UIGestureRecognizerStateFailed)
    {

        CGPoint center = currentView.center;
        CGPoint currentCenter = CGPointMake(center.x + translation.x, center.y);
        CGPoint offRight = CGPointMake(center.x + currentView.frame.size.width, center.y);
        CGPoint offLeft = CGPointMake(center.x - currentView.frame.size.width, center.y);

        CGPoint velocity = [gesture velocityInView:gesture.view.superview];

        if ((translation.x + velocity.x * 0.5) < (-self.containerView.frame.size.width / 2.0) && nextView)
        {
            // if we finished pan to left, reset transforms

            previousView.transform = CGAffineTransformIdentity;
            currentView.transform = CGAffineTransformIdentity;
            nextView.transform = CGAffineTransformIdentity;

            // set the starting point of the animation to pick up from where
            // we had previously transformed the views

            CGPoint nextCenter = CGPointMake(nextView.center.x + translation.x, nextView.center.y);
            currentView.center = currentCenter;
            nextView.center = nextCenter;

            // and animate the moving of the views to their final resting points,
            // adjusting the currentChildIndex appropriately

            [UIView animateWithDuration:0.25
                                  delay:0.0
                                options:UIViewAnimationOptionCurveEaseOut
                             animations:^{
                                 currentView.center = offLeft;
                                 nextView.center = center;
                                 self.currentChildIndex++;
                             }
                             completion:NULL];
        }
        else if ((translation.x + velocity.x * 0.5) > (self.containerView.frame.size.width / 2.0) && previousView)
        {
            // if we finished pan to right, reset transforms

            previousView.transform = CGAffineTransformIdentity;
            currentView.transform = CGAffineTransformIdentity;
            nextView.transform = CGAffineTransformIdentity;

            // set the starting point of the animation to pick up from where
            // we had previously transformed the views

            CGPoint previousCenter = CGPointMake(previousView.center.x + translation.x, previousView.center.y);
            currentView.center = currentCenter;
            previousView.center = previousCenter;

            // and animate the moving of the views to their final resting points,
            // adjusting the currentChildIndex appropriately

            [UIView animateWithDuration:0.25
                                  delay:0.0
                                options:UIViewAnimationOptionCurveEaseOut
                             animations:^{
                                 currentView.center = offRight;
                                 previousView.center = center;
                                 self.currentChildIndex--;
                             }
                             completion:NULL];
        }
        else
        {
            [UIView animateWithDuration:0.25
                                  delay:0.0
                                options:UIViewAnimationOptionCurveEaseInOut
                             animations:^{
                                 previousView.transform = CGAffineTransformIdentity;
                                 currentView.transform = CGAffineTransformIdentity;
                                 nextView.transform = CGAffineTransformIdentity;
                             }
                             completion:NULL];
        }
    }
}

看起来您是在进行上下平移，而不是我上面使用的左右平移，但希望您了解基本概念。

顺便说一句，在 iOS 6 中，您询问的用户界面（使用手势在视图之间滑动）可能可以使用内置容器控制器更有效地完成，UIPageViewController. 只需使用 的过渡样式UIPageViewControllerTransitionStyleScroll和 的导航方向UIPageViewControllerNavigationOrientationHorizontal。不幸的是，iOS 5 只允许页面卷曲过渡，而 Apple 只在 iOS 6 中引入了你想要的滚动过渡，但如果这就是你所需要的，UIPageViewController那么完成工作的效率甚至比我上面列出的还要高（你没有'不必进行任何自定义容器调用，无需编写手势识别器等）。

例如，您可以将“页面视图控制器”拖到情节提要上，创建一个UIPageViewController子类，然后在 中viewDidLoad，您需要配置第一页：

UIViewController *firstPage = [self.storyboard instantiateViewControllerWithIdentifier:@"1"]; // use whatever storyboard id your left page uses
self.viewControllerStack = [NSMutableArray arrayWithObject:firstPage];

[self setViewControllers:@[firstPage]
               direction:UIPageViewControllerNavigationDirectionForward
                animated:NO
              completion:NULL];

self.dataSource = self;

然后你需要定义以下UIPageViewControllerDataSource方法：

- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerAfterViewController:(UIViewController *)viewController
{
    if ([viewController isKindOfClass:[LeftViewController class]])
        return [self.storyboard instantiateViewControllerWithIdentifier:@"2"];

    return nil;
}

- (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerBeforeViewController:(UIViewController *)viewController
{
    if ([viewController isKindOfClass:[RightViewController class]])
        return [self.storyboard instantiateViewControllerWithIdentifier:@"1"];

    return nil;
}

您的实现会有所不同（至少不同的类名和不同的故事板标识符；我还让页面视图控制器在用户请求时实例化下一页的控制器，因为我没有保留对它们的任何强引用，当我完成转换到另一个页面时，它们将被释放......你也可以在启动时实例化它们，然后这些before和after例程显然不会实例化，而是在数组中查找它们），但希望你得到这个想法。

但关键问题是我没有任何手势代码，没有自定义容器视图控制器代码等。简单得多。

于 2013-04-01T17:06:05.833 回答