NSLog() to both console and file

Question

I would like to redirect NSog() to file, but still to see the output in console. I am aware that stderr can be redirected to file using:

freopen("file.log", "a+", stderr);

but after redirecting it to file, the log is no more shown in the console output.

I could build a custom wrapper around NSLog() but I would not get logged crash logs that are written to stderr in the moment of app crash.

I was also experimenting with dup() and other methods for duplicating file descriptors, but the output was ether in file or in console, never in both.

Similar questions was asked here: Write stderr on iPhone to both file and console but without accepted answer, or with suggestion to use a NSLog() wrapper.

Has anyone an idea on how to manage this work? Thanx in advance.

UPDATE: The most important part of redirecting is to have system error logs (stderr) written to both console and file.

Answer 1

According to the docs, you will need a custom log facility.

You need at a minimum, a function that takes variadic arguments and printd to NSLog and fprintf, something like:

void myLog(NSString* format, ...)
{
    va_list argList;
    va_start(argList, format);
    NSString* formattedMessage = [[NSString alloc] initWithFormat: format arguments: argList];
    va_end(argList);
    NSLog(@"%@", formattedMessage);
    fprintf(myFileDescriptor, "%s\n", [formattedMessage UTF8String]);
    [formattedMessage release]; // if not on ARC
}

Or there are Cocoa logging frameworks.

Looking for a Specific Cocoa Logging Framework