collectionView didSelectItemAtIn

在修改原来同事留下的代码，collectionView 所有代理都设置了，确保没有任何问题之后但就是不调用collectionView didSelectItemAtIndexPath代理方法；

最终发现他在collectionView上添加了UITapGestureRecognizer手势；

解决方案：UITapGestureRecognizer手势有个属性 tap.cancelsTouchesInView，默认是肯定的，设置为false即可；

苹果官方文档如下解释：

// default is YES. causes touchesCancelled:withEvent: or pressesCancelled:withEvent: to be sent to the view for all touches or presses recognized as part of this gesture immediately before the action method is called.

英文不好，不过大致意思应该是触摸事件被取消，也就是说触摸事件没有继续往下传递，自然didSelectItemAtIndexPath代理方法也就不会触发；

我的代码：

    UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleTapGesture:)];

    tap.numberOfTapsRequired = 1; // 单击

    tap.cancelsTouchesInView = false;

    [_mainCollectionView addGestureRecognizer:tap];