1.使用timeprofiler
https://onevcat.com/2012/01/testflight/
http://blog.csdn.net/fg313071405/article/details/8312772
http://www.cnblogs.com/wendingding/p/3766347.html
http://blog.csdn.net/face___book/article/details/50808620
http://www.cocoachina.com/ios/20150225/11163.html
