iOS中日志同步获取NSLog重定向以及其他详解

#define STDIN_FILENO 0 /* standard input file descriptor */
#define STDOUT_FILENO 1 /* standard output file descriptor */
#define STDERR_FILENO 2 /* standard error file descriptor */

NSLog(@"iOS NSLog");
fprintf (stderr, "%s\n", "fprintf log");

#import <asl.h>
// 从日志的对象aslmsg中获取我们需要的数据
+(instancetype)logMessageFromASLMessage:(aslmsg)aslMessage{
 SystemLogMessage *logMessage = [[SystemLogMessage alloc] init];
 const char *timestamp = asl_get(aslMessage, ASL_KEY_TIME);
 if (timestamp) {
  NSTimeInterval timeInterval = [@(timestamp) integerValue];
  const char *nanoseconds = asl_get(aslMessage, ASL_KEY_TIME_NSEC);
  if (nanoseconds) {
   timeInterval += [@(nanoseconds) doubleValue] / NSEC_PER_SEC;
  }
  logMessage.timeInterval = timeInterval;
  logMessage.date = [NSDate dateWithTimeIntervalSince1970:timeInterval];
 }
 const char *sender = asl_get(aslMessage, ASL_KEY_SENDER);
 if (sender) {
  logMessage.sender = @(sender);
 }
 const char *messageText = asl_get(aslMessage, ASL_KEY_MSG);
 if (messageText) {
  logMessage.messageText = @(messageText);//NSLog写入的文本内容
 }
 const char *messageID = asl_get(aslMessage, ASL_KEY_MSG_ID);
 if (messageID) {
  logMessage.messageID = [@(messageID) longLongValue];
 }
 return logMessage;
}
+ (NSMutableArray<SystemLogMessage *> *)allLogMessagesForCurrentProcess{
 asl_object_t query = asl_new(ASL_TYPE_QUERY);
 // Filter for messages from the current process. Note that this appears to happen by default on device, but is required in the simulator.
 NSString *pidString = [NSString stringWithFormat:@"%d", [[NSProcessInfo processInfo] processIdentifier]];
 asl_set_query(query, ASL_KEY_PID, [pidString UTF8String], ASL_QUERY_OP_EQUAL);
 aslresponse response = asl_search(NULL, query);
 aslmsg aslMessage = NULL;
 NSMutableArray *logMessages = [NSMutableArray array];
 while ((aslMessage = asl_next(response))) {
  [logMessages addObject:[SystemLogMessage logMessageFromASLMessage:aslMessage]];
 }
 asl_release(response);
 return logMessages;
}

- (void)redirectStandardOutput{
 //记录标准输出及错误流原始文件描述符
 self.outFd = dup(STDOUT_FILENO);
 self.errFd = dup(STDERR_FILENO);
#if BETA_BUILD
 stdout->_flags = 10;
 NSPipe *outPipe = [NSPipe pipe];
 NSFileHandle *pipeOutHandle = [outPipe fileHandleForReading];
 dup2([[outPipe fileHandleForWriting] fileDescriptor], STDOUT_FILENO);
 [pipeOutHandle readInBackgroundAndNotify];
 stderr->_flags = 10;
 NSPipe *errPipe = [NSPipe pipe];
 NSFileHandle *pipeErrHandle = [errPipe fileHandleForReading];
 dup2([[errPipe fileHandleForWriting] fileDescriptor], STDERR_FILENO);
 [pipeErrHandle readInBackgroundAndNotify];
 [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(redirectOutNotificationHandle:) name:NSFileHandleReadCompletionNotification object:pipeOutHandle];
 [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(redirectErrNotificationHandle:) name:NSFileHandleReadCompletionNotification object:pipeErrHandle];
#endif
}
-(void)recoverStandardOutput{
#if BETA_BUILD
 dup2(self.outFd, STDOUT_FILENO);
 dup2(self.errFd, STDERR_FILENO);
 [[NSNotificationCenter defaultCenter] removeObserver:self];
#endif
}
// 重定向之后的NSLog输出
- (void)redirectOutNotificationHandle:(NSNotification *)nf{
#if BETA_BUILD
 NSData *data = [[nf userInfo] objectForKey:NSFileHandleNotificationDataItem];
 NSString *str = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
 // YOUR CODE HERE... 保存日志并上传或展示
#endif
 [[nf object] readInBackgroundAndNotify];
}
// 重定向之后的错误输出
- (void)redirectErrNotificationHandle:(NSNotification *)nf{
#if BETA_BUILD
 NSData *data = [[nf userInfo] objectForKey:NSFileHandleNotificationDataItem];
 NSString *str = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
 // YOUR CODE HERE... 保存日志并上传或展示
#endif
 [[nf object] readInBackgroundAndNotify];
}

FILE * freopen ( const char * filename, const char * mode, FILE * stream );

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsPath = [paths objectAtIndex:0];
NSString *loggingPath = [documentsPath stringByAppendingPathComponent:@"/xxx.log"];
//redirect NSLog
freopen([loggingPath cStringUsingEncoding:NSASCIIStringEncoding], "a+", stderr);

// 重定向
int origin1 = dup(STDERR_FILENO);
FILE * myFile = freopen([loggingPath cStringUsingEncoding:NSASCIIStringEncoding], "a+", stderr);
// 恢复重定向
dup2(origin1, STDERR_FILENO);

- (dispatch_source_t)_startCapturingWritingToFD:(int)fd {
 int fildes[2];
 pipe(fildes); // [0] is read end of pipe while [1] is write end
 dup2(fildes[1], fd); // Duplicate write end of pipe "onto" fd (this closes fd)
 close(fildes[1]); // Close original write end of pipe
 fd = fildes[0]; // We can now monitor the read end of the pipe
 char* buffer = malloc(1024);
 NSMutableData* data = [[NSMutableData alloc] init];
 fcntl(fd, F_SETFL, O_NONBLOCK);
 dispatch_source_t source = dispatch_source_create(DISPATCH_SOURCE_TYPE_READ, fd, 0, dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0));
 dispatch_source_set_cancel_handler(source, ^{
  free(buffer);
 });
 dispatch_source_set_event_handler(source, ^{
  @autoreleasepool {
   while (1) {
    ssize_t size = read(fd, buffer, 1024);
    if (size <= 0) {
     break;
    }
    [data appendBytes:buffer length:size];
    if (size < 1024) {
     break;
    }
   }
   NSString *aString = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
   //printf("aString = %s",[aString UTF8String]);
   //NSLog(@"aString = %@",aString);
   // Do something
  }
 });
 dispatch_resume(source);
 return source;
}