iOS：我可以覆盖UIScrollView的捏合/缩小行为吗？ [英] iOS: Can I override pinch in/out behavior of UIScrollView?

问题描述

我在 UIView 上绘制图表，该图表包含在 UIScrollView 中，以便用户可以水平滚动以查看整个图形。

I'm drawing a graph on a UIView, which is contained by a UIScrollView so that the user can scroll horizontally to look around the entire graph.

现在我想在用户用两根手指插入时缩放图形，而不是在具有相同的视图中进行缩放对于X和Y方向的速率，我想通过改变X比例来仅在X方向上进行缩放，而不改变Y比例。

Now I want to zoom the graph when a user pinches in with two fingers, but instead of zooming in a view with the same rate for X and Y direction, I want to zoom only in the X direction by changing the X scale, without changing the Y scale.

我想我必须抓住捏合/缩小手势并重绘图形，覆盖默认的缩放行为。

I think I have to catch the pinch in/out gesture and redraw the graph, overriding the default zooming behavior.

但有没有办法做到这一点？

But is there a way to do this?

我一直很难在 UIScrollView 上捕捉捏手势，因为它在开始滚动时取消了触摸。我希望即使在 UIScrollView 取消触摸后，缩放也能正常工作。 :(

I've been having a very difficult time to catch the pinch gesture on the UIScrollView, as it cancels the touches when it starts to scroll. I want the zooming to work even after the UIScrollView cancels the touches. :(

谢谢，
Kura

Thanks, Kura

推荐答案

虽然你不能删除现有的捏手势识别器，你可以禁用它然后添加你自己的：

Although you cannot delete the existing pinch gesture recognizer, you can disable it and then add your own:

// Disable existing recognizer
for (UIGestureRecognizer* recognizer in [_scrollView gestureRecognizers]) {
    if ([recognizer isKindOfClass:[UIPinchGestureRecognizer class]]) {
        [recognizer setEnabled:NO];
    }
}

// Add our own
UIPinchGestureRecognizer* pinchRecognizer = 
  [[UIPinchGestureRecognizer alloc] initWithTarget:self 
                                            action:@selector(pinch:)];
[_scrollView addGestureRecognizer:pinchRecognizer];
[pinchRecognizer release];

然后在

- (void) pinch:(UIPinchGestureRecognizer*)recognizer { .. }

使用

[recognizer locationOfTouch:0 inView:..]
[recognizer locationOfTouch:1 inView:..]

来计算如果用户水平或垂直捏住，则输出。

to figure out if the user is pinching horizontally or vertically.

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