http://www.jianshu.com/p/ddc1a0b227a6
http://www.cocoachina.com/ios/20150311/11301.html
http://www.2cto.com/kf/201412/364350.html
http://www.jianshu.com/p/c86420f8e73c
http://blog.sina.com.cn/s/blog_6d58b63101015o6o.html
http://www.jianshu.com/p/0ddfa35c7898
【CoreData的剖析】http://blog.csdn.net/q199109106q/article/details/8563438/
