NSSearchPathForDirectoriesInDomains用法
http://blog.csdn.net/xingxing513234072/article/details/24184917
Documents
Library: Caches, Preferences
tmp
http://my.oschina.net/joanfen/blog/151145
iOS沙盒路径的查看和使用
原文：http://www.cnblogs.com/lushengcao/p/4842528.html
