LibComponentLogging-SystemLog is a logging class for Objective-C (Mac OS X and iPhone OS) which sends log messages to the Apple System Log facility (ASL). See man pages of asl, syslog, and syslogd for details about ASL.
LCLSystemLog can be used as a logging back-end for LibComponentLogging, but it is also useable as a standalone logging class without the Core files of LibComponentLogging.
With ASL, log messages are stored as structured messages in a data store. The syslog utility or the Console application can be used to retrieve messages from this data store, e.g.
syslog -F '$(Time) $(Sender)[$(PID):$(Thread)] $(Level0) $(Message) ($(Facility):$(File):$(Line))' -T utc -k Level0 -k Sender eq Example
retrieves all messages from the data store where the value associated with the 'Sender' key (the identifier of an application) is equal to 'Example' and where a value for the 'Level0' key exists. The key 'Level0' is used by LCLSystemLog to store the log level in addition to a mapped ASL priority level ('Level' key). All retrieved messages will be printed by using the UTC time format and the display format specified via -F. Example output:
2009.02.21 11:37:08 UTC Example[6717:10b] D Message 1 (example.f1:main.m:28) 2009.02.21 11:37:08 UTC Example[6717:10b] C Message 2 (example.f2:main.m:32) 2009.02.21 11:37:08 UTC Example[6717:10b] I Message 3 (example.f3:main.m:36)
By default, the default data store will only save log messages which have an ASL priority level between 'Emergency' and 'Notice' (level 0 to 5). Log messages with level 'Info' (level 6) or 'Debug' (level 7) will not be written to the data store. The command line
sudo syslog -c syslog -d
can be used to tell syslogd to store messages up to priority level 'Debug'.
Alternatively, LCLSystemLog can be configured to use only ASL priority levels up to a specific last level, e.g. 'Notice'. All log messages with a higher level will be mapped to the configured last level, e.g. 'Debug' messages will be logged with the ASL level 'Notice' while the 'Level0' field will still contain the level information 'Debug'.
Before you start, copy the LCLSystemLog.h and .m file to your project and create a LCLSystemLogConfig.h configuration file (based on the packaged template file).
Then, import the LCLSystemLog.h in your source files or in your prefix header file if you are using LCLSystemLog as a standalone logging class, or add an import to your lcl_config_logger.h file if you are using the class as a logging back-end for LibComponentLogging.
In case you are using the LCLSystemLog class with LibComponentLogging, you can simply start logging to ASL by using the standard logging macro from LibComponentLogging, e.g.
lcl_log(lcl_cMyComponent, lcl_vError, @"message ...");
If you are using the class as a standalone logger, you can simply call one of the log... methods from the LCLSystemLog class, e.g.
[LCLSystemLog logWithIdentifier:"MyComponent" level:1 ... format:@"message ...", ...];
or you can wrap these calls into your own logging macros.
The Git repository contains the following branches:
master: The master branch contains stable builds of the main logging code which are tagged with version numbers.
devel: The devel branch is the development branch for the logging code which contains an Xcode project with dependent code, e.g. the Core files of LibComponentLogging, and unit tests. The code in this branch is not stable.
The following Git repositories are related to this repository:
- http://github.com/aharren/LibComponentLogging-Core: Core files of LibComponentLogging.
Copyright and License
Copyright (c) 2008-2013 Arne Harren firstname.lastname@example.org
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