Can NSLog be disabled from appearing in device's console?

Question

I have a builded application that is running on device. I open device's console view in XCode's Organizer window. I assume (for the sake of this question) that NSLog(@"Some string") gets called.

Is there any way, may be an option in device, or application's settings, that would disable this log from appearing in console?

Edit: I'm not interested in replacing NSLog by other solution that can achieve this effect. The purpose of this question is to fully understand NSLog's functionality.

@Wain this would be useful if the purpose of my question was to achieve this effect — hide NSLogs from console. It's not. — Max Yankov, Jan 20 '14 at 12:10
That's what it does. NSLog itself doesn't offer any options so you need some wrapper around it so you can disable logs on demand or for your release build. — Wain, Jan 20 '14 at 12:13
I don't want to disable logs. I want to understand how they could, theoretically, be disabled, so I would understand why don't they show up when they should. — Max Yankov, Jan 20 '14 at 12:17
There is no setting (as far as I know) that disables NSLog. But the logs ultimately are printed to stderr, so closing or redirecting stderr would have such an effect, compare trojanfoe's answer below. — Martin R, Jan 20 '14 at 12:37

trojanfoe · Answer 1 · 2014-01-20T13:19:33.763

(Thanks to @MartinR for encouraging me to pull my finger out on this answer and to correctly identify that you cannot just close stdout/stderr, as the next open() will re-use those file descriptors, but to redirect stdout/stderr to the infamous /dev/null).

logControl.h:

#pragma once

extern void stopLogging();
extern void startLogging();

logControl.c:

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

static int loggingStopped = 0;
static int oldStdout = -1;
static int oldStderr = -1;

void stopLogging() {
    if (!loggingStopped) {
        oldStdout = dup(1);
        oldStderr = dup(2);

        int devNull = open("/dev/null", O_WRONLY);
        dup2(devNull, 1);
        dup2(devNull, 2);
        close(devNull);

        loggingStopped = 1;
    }
}

void startLogging() {
    if (loggingStopped && oldStdout >= 0 && oldStderr >= 0) {
        dup2(oldStdout, 1);
        close(oldStdout);
        oldStdout = -1;

        dup2(oldStderr, 2);
        close(oldStderr);
        oldStderr = -1;

        loggingStopped = 0;
    }
}

This works at runtime, not compile time, which I believe is what you are asking. Simply call stopLogging() or startLogging() as required.

NOTE: There is no error-checking to speak of, so that could be improved perhaps.

Better use dup2() to "redirect" stderr to /dev/null. Otherwise the next file opened will reuse these file descriptors. See http://stackoverflow.com/a/12611692/1187415 for an example. — Martin R, Jan 20 '14 at 12:31
@MartinR Yeah, I think you're right. You'd have to save the old stdout and stderr as well, in case you wanted to re-open it. Doesn't matter - this answer isn't well-liked anyway ;-) — trojanfoe, Jan 20 '14 at 12:32
The problem might be that it is unclear (and misunderstood by some people) what answer the OP expects. To me yours seems to come closest to a possible answer. — Martin R, Jan 20 '14 at 12:34

score 0 · Answer 2 · edited May 23 '17 at 12:11

0

Add this line given below in your .pch file in Xcode.

   #define NSLog(...)

It will disable all NSLogs.

for more alternatives see the link

edited May 23 '17 at 12:11

Community

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1

answered Jan 20 '14 at 12:13

Ankush

2,405
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score 0 · Answer 3 · answered Jan 20 '14 at 13:46

0

#if TARGET_IPHONE_SIMULATOR

//Simulator

#else

// Device
#define NSLog
#endif

Add this in your .pch file this will disable NSLog only for device alone not for simulator.

answered Jan 20 '14 at 13:46

CoolMonster

2,258
25
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score 0 · Answer 4 · answered Jan 24 '14 at 14:22

Add below code to .pch file

#ifdef DEBUG
#    define NSLog(...) NSLog(__VA_ARGS__)
#else
#   define NSLog(...) /* */
#endif

And in Build Settings, search "Preprocessor Macros" and remove "DEBUG=1" written in it.

and Thats it, you will not see any logs in your console now.

Can NSLog be disabled from appearing in device's console?

4 Answers4