Setting a flag in compiler for NSLog not to show

Question

Is there any particular flag which can be set to not display NSLog output in either debug or release?

Thanks.

Answer 1

Default flag with a new Xcode project is DEBUG for Debug and none for Release. So you will hide NSLog in Release this way:

#ifndef DEBUG
#   define NSLog(...)
#   define NSLogv(...)
#endif

Or if you want pretty custom logs as well (not using #ifdef here because no simple #elifdef):

#if DEBUG
#   define NSLog(format, ...) NSLog((@"%s " format), __PRETTY_FUNCTION__, ##__VA_ARGS__)
#   define NSLogv(format, ...) NSLog(@"%s %@", __PRETTY_FUNCTION__, [[NSString alloc] initWithFormat:format arguments:__VA_ARGS__])
#elif ADHOC
    // default logs
#else// Release
#   define NSLog(...)
#   define NSLogv(...)
#endif

And if you want to override those macros and still log something sometimes, you can use:

(NSLog)(@"This log is always visible!");

Now, how to hide those as well? It would require you to #define NSLog NoLog and define NoLog as an extern function with an empty implementation like void NoLog(NSString *format, ...) {}. But it could be cleaner to avoid using (NSLog) altogether and instead use a function with a LogLevel enum:

typedef NS_ENUM(NSUInteger, LogLevel) {
    LogLevelRelease,
    LogLevelAdHoc,
    LogLevelDeveloper,
};

void CustomLog(LogLevel level, NSString *format, ...) {
#if !DEBUG
    if (LogLevel == LogLevelDeveloper)
        return;
#if !ADHOC
    if (LogLevel == LogLevelAdHoc)
        return;
#endif
#endif
    va_list ap;
    va_start (ap, format);
    NSLogv(format, ap);
    va_end (ap);
}

The drawback of this CustomLog is that arguments get always evaluated, even in Release. So an optimal solution is multiple macros:

#define NSLog(format, ...) NSLog((@"%s " format), __PRETTY_FUNCTION__, ##__VA_ARGS__)
#if DEBUG
#   define DebugLog(...) NSLog(__VA_ARGS__)
#   define AdHocLog(...) NSLog(__VA_ARGS__)
#   define ReleaseLog(...) NSLog(__VA_ARGS__)
#elif ADHOC
#   define DebugLog(...)
#   define AdHocLog(...) NSLog(__VA_ARGS__)
#   define ReleaseLog(...) NSLog(__VA_ARGS__)
#else// Release
#   define NSLogv(...)
#   define DebugLog(...)
#   define AdHocLog(...)
#   define ReleaseLog(...) NSLog(__VA_ARGS__)
#endif