Enable and Disable NSLog in DEBUG mode

问题

I want to enable NSLog when I am in debug and disable it otherwise. A very simple thing is:

#ifdef DEBUG
NSLog(@"My log");
#endif

But all this #ifdef and #endif is borring... :( So I try other thing: (.pch is good place to put it)

#ifdef DEBUG
#   define NSLog(text) NSLog(text);
#else 
#   define NSLog(text) 
#endif

This work very fine (isn't recursive). But the problem is that NSLog have infinite arguments.

void NSLog(NSString *format, ...)

How I solve this to work in preprocessor mode?

-- Edit --

This code make your NSLog better:

#ifdef DEBUG
    #define NSLog(FORMAT, ...) fprintf(stderr,"%s\n", [[NSString stringWithFormat:FORMAT, ##__VA_ARGS__] UTF8String]);
#else
    #define NSLog(...)
#endif

回答1:

This should do the trick:

 #ifdef DEBUG
 #   define NSLog(...) NSLog(__VA_ARGS__)
 #else 
 #   define NSLog(...) (void)0
 #endif

回答2:

This is a bit shorter and also disables NSLog when using a device. If you're writing a game, NSLogs sent often can reduce your FPS from 60 to 20.

#if !defined(DEBUG) || !(TARGET_IPHONE_SIMULATOR)
    #define NSLog(...)
#endif

回答3:

All the above answers are correct. I can suggest you to do it in a following way also. Suppose i have a if statement with no brackets

if(x==5)
NSLog("x is 5");

What will happen if it will replace NSLog with no statement. So we can simply replace it with an empty loop.

#ifdef DEBUG
#define NSLog(...) NSLog(__VA_ARGS__)
#else
#define NSLog(...) do {} while (0)
#endif

This statement will run an empty loop once. This will safely remove your NSLog from all of your live code.

回答4:

#ifndef Debug
    #define Debug 1
#endif

#if Debug
#   define DebugLog(fmt, ...) NSLog((@"%s [Line %d] " fmt), __PRETTY_FUNCTION__, __LINE__, ##__VA_ARGS__);
#else
#   define DebugLog(...)
#endif

Set Debug to 1 for enabling the log and 0 for disabling it.

回答5:

Here is a nice trick... add to any .m

#define EXTRANSLog if([[NSUserDefaults standardUserDefaults] boolForKey:@"SomeFancyKey"] == YES) NSLog

Replace any

NSLog(@"????");

with

EXTRANSLog(@"????");

In this example, I created a NSUser key and set the BOOL to YES,, use some form of switch etc to change the key to NO or remove altogether if you don't want to view the EXTRANSLog's via console debugger.

I use this when troubleshooting and don't want all the excessive logs to appear. Only when SomeFancyKey == YES.

This is the same as

#define NSLog if(1) NSLog

where 1 is YES show NSLog, and 0 is NO.

来源：https://stackoverflow.com/questions/6552197/enable-and-disable-nslog-in-debug-mode

标签

objective-c

cocoa

nslog