手势冲突UIPanGestureRecognizer 和UIPinchGestureRecognizer

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;
}