iphone - CocoaTouch 中的拉菜单

Question

我正在尝试制作一个 UIView/UIControl，人们可以向上拖动并显示文本框，然后向下拖动以隐藏它。然而，我还没有找到一种方法来使这种“流动”——它似乎总是停在随机的地方并且不允许任何更多的运动。目前我正在使用 UIView 作为 View 的顶部部分，这是当前的代码:

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {

 UITouch *touch = [touches anyObject];

 if ([touch view] == topMenuView) {
  CGPoint location = [touch locationInView:self.superview];

  CGPoint locationInsideBox = [touch locationInView:self];

  CGPoint newLocation = location;
  newLocation.x = self.center.x;
  newLocation.y = newLocation.y + (self.frame.size.height - locationInsideBox.y) / 2;

  if ((self.superview.frame.size.height - newLocation.y) < (self.frame.size.height / 2) && (self.superview.frame.size.height - newLocation.y) > -32)
  {
   self.center = newLocation;
  }
  return;
 }
}

任何帮助将不胜感激!

Answer 1

我会使用平移手势识别器。以下代码将简单地随着用户的手指上下移动 View 。如果您想限制它向上移动的距离，请让它快速放置或具有您需要添加的动量。

UIView * view; // The view you're moving
CGRect originalFrame; // The frame of the view when the touch began

- (void) pan:(UIPanGestureRecognizer *)pan {
    switch (pan.state) {
        case UIGestureRecognizerStateBegan: {
            originalFrame = view.frame;
        } break;

        case UIGestureRecognizerStateChanged:
        case UIGestureRecognizerStateEnded: {
            CGPoint translation = [pan translationInView:view];
            CGRect frame = originalFrame;
            frame.origin.y += translation.y;
            view.frame = frame;
        } break;
    }
}