UIButton拖动响应事件，距离问题

UIControlEventTouchDragInside当一次触摸在控件窗口内拖动时。UIControlEventTouchDragOutside当一次触摸在控件窗口之外拖动时。UIControlEventTouchDragEnter当一次触摸从控件窗口之外拖动到内部时。UIControlEventTouchDragExit当一次触摸从控件窗口内部拖动到外部时。

[btn addTarget:self action:@selector(sendButtonDrag:withEvent:) forControlEvents:UIControlEventTouchDragInside];
[btn addTarget:self action:@selector(sendButtonDrag:withEvent:) forControlEvents:UIControlEventTouchDragOutside];

• (IBAction)sendButtonDrag:(UIButton *)sender withEvent:(UIEvent *)event {
  if ([self isInButtonBounds:sender event:event]) {
  // 在里面
  } else {
  // 在外面
  }
  }

• (BOOL)isInButtonBounds:(UIButton *)button event:(UIEvent *)event {
  UITouch *touch = [[event allTouches] anyObject];
  CGFloat boundsExtension = 5.0f; //扩展范围阀值
  CGRect outerBounds = CGRectInset(button.bounds, -1 * boundsExtension, -1 * boundsExtension);
  BOOL touchOutside = !CGRectContainsPoint(outerBounds, [touch locationInView:button]);
  if (touchOutside) {
  BOOL previewTouchInside = CGRectContainsPoint(outerBounds, [touch previousLocationInView:button]);
  if (previewTouchInside) {
  // UIControlEventTouchDragExit
  } else {
  // UIControlEventTouchDragOutside
  }
  return NO;
  } else {
  BOOL previewTouchOutside = !CGRectContainsPoint(outerBounds, [touch previousLocationInView:button]);
  if (previewTouchOutside) {
  // UIControlEventTouchDragEnter
  } else {
  // UIControlEventTouchDragInside
  }
  return YES;
  }
  }

• (IBAction)sendAudioRecordButton:(id)sender withEvent:(UIEvent *)event {
  if ([self isInButtonBounds:sender event:event]) {
  // 点击按钮
  }
  }