源于iOS App开发时，控制台日志混乱，不便于分析的需要，产生了这篇文章。

基础票

说说NSLog

调用NSLogv ＝> Logs an error message to the Apple System Log facility.
Output from NSLogv is serialized, in that only one thread in a process can be doing the writing/logging described above at a time.
- STDERR_FILENO
- ASL

iOS日志重定向到文件

{
    //to log to document directory
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsPath = [paths objectAtIndex:0];
    NSString *loggingPath = [documentsPath stringByAppendingPathComponent:@"/mylog.log"];
    NSLog(@"%@", loggingPath);
    //redirect NSLog
    freopen([loggingPath cStringUsingEncoding:NSASCIIStringEncoding], "a+", stderr);
}

这样我们就可以在电脑上面直接tail -f这个文件，配合grep等命令进行日志分析了。

不进行日志重定向

iOS模拟器的日志其实是输出到系统中某个文件中了，好像是定时压缩一个保存起来，我们只要找到那个文件就可以tailf了。

system.log文件在哪儿.png

根据当前模拟器的identifier(windows-devices菜单)按图示找到当前模拟器腺癌的system.log文件，右键finder显示，然后直接tailf就可以啦。

如何更方便呢？

To give yourself faster access to logs via terminal, you can add an alias to your .bash_profile file by typing:
echo "alias simulatorlog='tail -f ~/Library/Logs/iOS\ Simulator/7.0/system.log'" >> ~/.bash_profile
After it you can simply type simulatorlog into terminal window to access the logs.
像我自己的电脑，是这样配的(查看iPhone6的日志)：
alias mylog6='tail -f /Users/test/Library/Logs/CoreSimulator/0A5E599A-D202-4502-8E3C-B6E97840E7ED/system.log'
查看日志时，直接mylog6 | grep something
Enjoy.

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分享篇

下面是组内分享时用的md文件，是一个大概的总结性的东西，虽然没有详细的展开（分享时口说呗，写起来好累赘的样子），但感觉对于理思路还是挺好的。

Basic Loggers Related（主要是Logger分类）

Apple System Logger
Standard output
standard error
File Logger
HTTP Server Logger
Telnet Server Logger
- Telnet协议是TCP/IP协议族中的一员，是Internet远程登陆服务的标准协议和主要方式。它为用户提供了在本地计算机上完成远程主机工作的能力。在终端使用者的电脑上使用telnet程序，用它连接到服务器。终端使用者可以在telnet程序中输入命令，这些命令会在服务器上运行，就像直接在服务器的控制台上输入一样。
TCP Server Logger
UDP Server Logger
TCP Client Logger
UDP Client Logger
Onscreen Logging Overlay
Custom Loggers
Custom Logger fomatters

Basic Libraries Related（理清这几个库的关系）

^_
- CocoaLumberjack
^_
- XLFacility
- GCDNetworking
  - GCDNetworking is a networking framework based on GCD available under a friendly New BSD License.
- GCDWebServer
  - GCDWebServer is a modern and lightweight GCD based HTTP 1.1 server designed to be embedded in OS X & iOS apps.
- GCDTelnetServer
  - GCDTelnetServer is a drop-in embedded Telnet server for iOS and OS X apps.
^_
- CocoaAsyncSocket
  - CocoaAsyncSocket provides easy-to-use and powerful asynchronous socket libraries for Mac and iOS. The classes are described below.
  - GCDAsyncSocket is a TCP/IP socket networking library built atop Grand Central Dispatch.
  - GCDAsyncUdpSocket is a UDP/IP socket networking library built atop Grand Central Dispatch.
  - 日志实现用了CocoaLumberjack
- CocoaHTTPServer（FMock工具用的这个）
  - CocoaHTTPServer is a small, lightweight, embeddable HTTP server for Mac OS X or iOS applications.
  - 底层实现用了CocoaAsyncSocket
- RoutingHTTPServer
  - A routing API for CocoaHTTPServer
  - 底层实现用了CocoaHTTPServer

Guide（演示内容）

XLFacility --> HTTPServer
- http://127.0.0.1:8080
XLFacility --> TelnetServer
- telnet localhost 2323
XLFacility --> Onscreen Logging Overlay
CocoaLumberjack --> UDPClient
- start udp server
- test udp client logger
- 下面是一个简单的udp server代码：

#!/usr/bin/env python
# UDP Echo Server -  udpserver.py
# code by www.cppblog.com/jerryma
import socket, traceback

host = '127.0.0.1'
port = 8888

s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
s.bind((host, port))

while 1:
    try:
        message, address = s.recvfrom(8192)
        print "Got data from", address, ": ", message
        s.sendto(message, address)
    except (KeyboardInterrupt, SystemExit):
        raise
    except:
        traceback.print_exc()

iOS 日志分析