如何控制工程中的LOG信息，并写入文件

//

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//
TFLog.h

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//

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//
Created by Tom Fewster on 08/06/2010.

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//

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#if
TARGET_OS_IPHONE || TARGET_IPHONE_SIMULATOR

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#
import <UIKit/UIKit.h>

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#else

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#
import <Cocoa/Cocoa.h>

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#endif

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#ifdef
DEBUG

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#
define DebugLog(format, ...) NSLog(@"<Debug>: " format @" [" __FILE__ @":%i]", ##__VA_ARGS__, __LINE__)

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#
ifdef TRACE_LOG

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#
define DebugTrace(format, ...) NSLog(@"<Trace>: " format @" [" __FILE__ @":%i]", ##__VA_ARGS__, __LINE__)

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#
else

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#
define DebugTrace(format, ...)

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#
endif

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#
define InfoLog(format, ...) NSLog(@"<Info> " format @" [" __FILE__ @":%i]", ##__VA_ARGS__, __LINE__)

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#
define WarningLog(format, ...) NSLog(@"<Warning> " format @" [" __FILE__ @":%i]", ##__VA_ARGS__, __LINE__)

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#
define ErrorLog(format, ...) NSLog(@"<Error> " format @" [" __FILE__ @":%i]", ##__VA_ARGS__, __LINE__)

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#else

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#
define DebugLog(format, ...)

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#
define DebugTrace(format, ...)

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#
define InfoLog(format, ...) NSLog(@"<Info>: " format, ##__VA_ARGS__)

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#
define WarningLog(format, ...) NSLog(@"<Warning>: " format, ##__VA_ARGS__)

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#
define ErrorLog(format, ...) NSLog(@"<Error>: " format, ##__VA_ARGS__)

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#endif

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void
initialiseLogger(void);

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//

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//
TFLog.m

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//

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//
Created by Tom Fewster on 06/04/2012.

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//

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#import
"TFLog.h"

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#include
<assert.h>

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#include
<stdbool.h>

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#include
<sys/types.h>

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#include
<unistd.h>

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#include
<sys/sysctl.h>

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void
initialiseLogger(void) {

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#ifdef
DEBUG

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int
junk;

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int
mib[4];

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struct
kinfo_proc   info;

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size_t
size;

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//
Initialize the flags so that, if sysctl fails for some bizarre

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//
reason, we get a predictable result.

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info.kp_proc.p_flag
= 0;

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//
Initialize mib, which tells sysctl the info we want, in this case

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//
we're looking for information about a specific process ID.

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mib[0]
= CTL_KERN;

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mib[1]
= KERN_PROC;

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mib[2]
= KERN_PROC_PID;

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mib[3]
= getpid();

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//
Call sysctl.

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size
= sizeof(info);

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junk
= sysctl(mib, sizeof(mib) / sizeof(*mib), &info, &size, NULL, 0);

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assert(junk
== 0);

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//
We're being debugged if the P_TRACED flag is set.

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//
so, if we are being debugged the out put will go to Xcode's console

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//
other wise redirect it to a file in our documents directory

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if
(!((info.kp_proc.p_flag & P_TRACED) != 0)) {

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//
find our applications documents directory

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NSArray
*paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);

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NSString
*documentsDirectory = [paths objectAtIndex:0];

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//
create a unique files name keyed off the date

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NSDateFormatter
*dateFormatter = [[NSDateFormatter alloc] init];

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[dateFormatter
setDateFormat:@"yyyyMMddHHmmss"];

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NSString
*fileName = [NSString stringWithFormat:@"%@.log", [dateFormatter stringFromDate:[NSDate date]]];

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NSString
*logFilePath = [documentsDirectory stringByAppendingPathComponent:fileName];

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//
redirect stderr to our new file

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freopen([logFilePath
cStringUsingEncoding:NSASCIIStringEncoding],"a+",stderr);

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}

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#endif

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}