iOS:用于平滑滚动和轻弹视图的手势识别器

Question

我正在构建一个iPad应用程序,我需要允许使用两个视图之间提供的分隔视图来调整视图功能.分隔视图只是两个半屏内容视图之间的20px高度视图 - 请参阅附图.

当用户向上或向下滚动此分隔视图时,两个内容视图都会相应地更改其大小.我UIView使用touchMoved委托扩展并实现了这个代码作为代理下面给出的代码touchesMoved.它工作正常.唯一缺少的TouchMoved是你不能直接将分频器视图轻弹到顶部或底部.你必须一直拖到顶部或底部!

为了支持轻弹我尝试过的视图,UIPanGestureRecognizer但我看不到它的平滑拖动.设置父级的拆分位置会调整两个内容视图,如代码中所示.当我处理UIGestureRecognizerStateChanged状态中的分割位置变化时,只需触摸分割器视图就可以将其轻弹到顶部或底部.处理拆分位置更改UIGestureRecognizerStateEnded是相同的,但我没有看到内容视图调整dividerview滚动调整大小!

有人可以请告诉我如何通过调整内容视图(如touchMoved)和轻弹视图来实现分隔视图的平滑滚动？任何替代方法也可以.谢谢.

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
    UITouch *touch = [touches anyObject];
    if (touch) {
        CGPoint lastPt = [touch previousLocationInView:self];
        CGPoint pt = [touch locationInView:self];
        float offset = pt.y - lastPt.y;
        self.parentViewController.splitPosition = self.parentViewController.splitPosition + offset;
    }
}

- (void)handlePan:(UIPanGestureRecognizer*)recognizer {

    CGPoint translation = [recognizer translationInView:recognizer.view];
    CGPoint velocity = [recognizer velocityInView:recognizer.view];

    if (recognizer.state == UIGestureRecognizerStateBegan) {
    } else if (recognizer.state == UIGestureRecognizerStateChanged) {
       // If I change split position here, I don't see smooth scrolling dividerview...it directly jumps to the top or bottom!
       self.parentViewController.splitPosition = self.parentViewController.splitPosition + translation.y;
    } else if (recognizer.state == UIGestureRecognizerStateEnded) {
      // If I change split position here, the same thing happens at end and I don't see my divider view moving with my scrolling and resizing my views.
        self.parentViewController.splitPosition = self.parentViewController.splitPosition + translation.y;
    }
}

初始屏幕

通过向底部滚动分隔视图来增加顶视图大小.

顶视图完全隐藏在这里,但我必须滚动分隔视图一直到顶部.我想轻弹分隔视图,使其直接从任何位置移动到顶部

Answer 1

如果我理解正确,你在这里有两个不同的问题.

1st:使用GestureRecognizer时"不平滑"的拖动.代码中的问题是,每次GR调用它的句柄方法时都会添加转换.由于平移是连续测量的,因此每次调用时都会增加一个更高的值(即第一个调用将10添加到分割位置,第二个调用增加20,第三个30等等).

要解决此问题,您应该在更新拆分位置后将转换设置为零:

- (void)handlePan:(UIPanGestureRecognizer*)recognizer {

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

    if (recognizer.state == UIGestureRecognizerStateChanged) {
       self.parentViewController.splitPosition = self.parentViewController.splitPosition + translation.y;
    } 
    [recognizer setTranslation:CGPointZero inView:recognizer.view];
}

第二步:要允许用户将分割位置轻弹到顶部或底部,您可以检查UIGestureRecognizerStateEnded中的速度,如果它执行某个值,则立即将分割位置设置为顶部或底部.

但是使用UISwipeGestureRecognizer可能更方便.

- (void)handleSwipe:(UISwipeGestureRecognizer *)gr
{
    if (gr.direction == UISwipeGestureRecognizerDirectionUp){
        [self.parentViewController moveSplitViewToTop];
    }
    else if (gr.direction == UISwipeGestureRecognizerDirectionDown){
        [self.parentViewController moveSplitViewToBottom];
    }
}

在这种情况下,可能有必要(不确定,可能不是)通过设置要求SwipeGR在PanGR触发之前失败:

[panGestureRecognizer requireGestureRecognizerToFail:swipeGestureRecognizer];

希望有所帮助.

编辑:关于你的评论,我假设频率你的意思是速度.如果你只使用PanGR,你可以将上面的代码修改为...... 像这样:

- (void)handlePan:(UIPanGestureRecognizer*)recognizer {

    CGPoint translation = [recognizer translationInView:recognizer.view];
    CGPoint velocity = [recognizer velocityInView:recognizer.view];

    if (recognizer.state == UIGestureRecognizerStateChanged) {
       self.parentViewController.splitPosition = self.parentViewController.splitPosition + translation.y;
    } 
    else if (recognizer.state == UIGestureRecognizerStateEnded){
        if (velocity.y > someValue){
            [self.parentViewController moveSplitViewToBottom];
        }
        else if (velocity.y < someValue){
            [self.parentViewController moveSplitViewToTop];
        }
    }
    [recognizer setTranslation:CGPointZero inView:recognizer.view];
}

我不确定速度是否已签名,如果不是,你必须在if-block中再次检查转换.