ios - 垂直 ScrollView 内的水平平移

Question

我有一个仅限于垂直滚动的 ScrollView 。在它里面，我想要有一个 UIPanGestureRecognizer 的 View 只识别水平平移。

与水平识别器一样，它会获胜并阻止 ScrollView 滚动。

如果检测到主要是水平手势，我希望水平平移获胜，否则垂直滚动应该获胜。与 Mailbox 的工作方式非常相似，或者在 iOS8 Mail.app 中滑动

Answer 1

您可以使用 UIGestureRecognizerDelegate 方法之一，例如 gestureRecognizerShouldBegin: 来指定在哪种情况下触发哪个平移手势。

- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer {

    // If the gesture is a pan, determine whether it starts out more
    // horizontal than vertical than act accordingly
    if ([gestureRecognizer isKindOfClass:[UIPanGestureRecognizer class]]) {

        UIPanGestureRecognizer *panGestureRecognizer = (UIPanGestureRecognizer *)gestureRecognizer;
        CGPoint velocity = [panGestureRecognizer velocityInView:self.view];

        if (gestureRecognizer == self.scrollView.panGestureRecognizer) {
            // For the vertical scrollview, if it's more vertical than
            // horizontal, return true; else false
            return fabs(velocity.y) > fabs(velocity.x);
        } else {
            // For the horizontal pan view, if it's more horizontal than
            // vertical, return true; else false
            return fabs(velocity.y) < fabs(velocity.x);
        }
    }
    else
        return YES;
}