I started my iOS dev (it calls iPhone dev then) from May, 2009. I composed a logger utility for debugging and tracing. I used them within 2 iOS apps and it gives me a lot of help. Today I want to open source it to public.

License: MIT

Install:
(1) Add GRLogger.h, GRLogger.m and License into your project (2) Sample -- Please refer to main.m

#import "GRLogger.h"
int foo()
{
  ENTER(@"foo");
  RETURN(10, @"foo");
}

int main(int argc, char *argv[])
{
  @autoreleasepool {
    SETLOGLEVEL(SLLS_ALL);
    INFO(@"info");
    DBG(@"debug value is %d", 3);
    WARN(@"warning");
    ERROR(@"error");
    FATAL(@"fatal");
    LOG(SLL_TINY, @"tiny");
    foo();
    return UIApplicationMain(argc, argv, nil, NSStringFromClass([AppDelegate class]));
   }
}

The output is as below:
2012-05-29 01:10:42.859 GRLogger[42610:f803] FILE:main.m LINE:25 [INFO] info
2012-05-29 01:10:42.867 GRLogger[42610:f803] FILE:main.m LINE:26 [DEBUG] debug value is 3
2012-05-29 01:10:42.868 GRLogger[42610:f803] FILE:main.m LINE:27 [WARN] warning
2012-05-29 01:10:42.869 GRLogger[42610:f803] FILE:main.m LINE:28 [ERROR] error
2012-05-29 01:10:42.870 GRLogger[42610:f803] FILE:main.m LINE:29 [FATAL] fatal
2012-05-29 01:10:42.872 GRLogger[42610:f803] FILE:main.m LINE:30 [TINY] tiny
2012-05-29 01:10:42.873 GRLogger[42610:f803] FILE:main.m LINE:17 [ENTER] foo
2012-05-29 01:10:42.874 GRLogger[42610:f803] FILE:main.m LINE:18 [RETURN] foo

Documentation:
(1) SETLOGLEVEL(SLLS_ALL);

typedef enum {
SLLS_ALL = 0,
SLLS_MAJOR = 45,
SLLS_MINOR = 65,
SLLS_NONE = 1000,
SLLS_DEFAULT = SLLS_MAJOR // SLLS_DEFAULT = SLLS_MAJOR
} GRLoggerLevelSetting;
If you set values other than GRLoggerLevelSetting, it uses SLLS_DEFAULT Usually we use SLLS_ALL, SLLS_MAJOR (just INFO, WARN, ERROR, FATAL) and SLLS_NONE.

(2) If you want to close GRLogger, you have 2 approaches:

• SETLOGLEVEL(SLLS_NONE);
• defined SELF_DEFING_CLOSEGRLOGGER (better)

TODO: (1) Support log into files