在dealloc 中报错 It is possible that this object was over-released, or is in the process of deallocation.
问题代码：
[self.popView removeFromSuperview];
self.popView = nil;
分析原因，因为我没有使用到self.popView，self.popView在dealloc中会先初始化，这时候就报错了。
解决方法：
[_popView removeFromSuperview];
self.popView = nil;
