当同时使用pan和pin手势时假如冲突，需要加入下面方法
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer {
return YES;
}
手势冲突UIPanGestureRecognizer 和UIPinchGestureRecognizer
原文：http://www.cnblogs.com/levy/p/4708794.html