需求：获取 app 运行时输出日志，包含接入的其余 SDK 的输出，方便开发人员在出现问题的时候，获得详细的Log信 息，快速的识别出问题的缘由并修复和优化等。 一番 google 后有两种方案，一种是非侵入性的，不影响 app 链接 xcode 调试时各类信息的输出，一种是重定向，会致使输出信息在调试时看不到，各有优缺点。 1、ASL 直接获取 咱们能够经过官方文档了解到，OC中最多见的NSLog操做会同时将标准的Error输出到控制台和系统日志(syslog)中(C语言的printf 系列函数并不会，swift的printf为了保证性能也只会在模拟器环境中输出)。其内部是使用Apple System Logger(简称ASL)去实现的，ASL是苹果本身实现的用于输出日志到系统日志库的一套API接口，有点相似于SQL操做。在iOS真机设备上，使用ASL记录的 log被缓存在沙盒文件中，直到设备被重启，通常会输出到系统的 /var/log/syslog 文件中。swift
#import <asl.h>
+(NSArray*)console
{
NSMutableArray *consoleLog = [NSMutableArray array];
aslclient client = asl_open(NULL, NULL, ASL_OPT_STDERR);
aslmsg query = asl_new(ASL_TYPE_QUERY);
asl_set_query(query, ASL_KEY_MSG, NULL, ASL_QUERY_OP_NOT_EQUAL);
aslresponse response = asl_search(client, query);
asl_free(query);
aslmsg message;
while((message = asl_next(response)) != NULL)
{
SystemLogMessage *model = [self logMessageFromASLMessage:message];
[consoleLog addObject:model];
}
if (message != NULL) {
asl_free(message);
}
asl_free(response);
asl_close(client);
return consoleLog;
}
//这个是怎么从日志的对象aslmsg中获取咱们须要的数据
+(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;
NSDateFormatter *format = [NSDateFormatter new];
format.dateFormat = @"YYYY-MM-dd hh:mm:ss";
logMessage.date = [NSDate dateWithTimeIntervalSince1970:timeInterval];
logMessage.dateTime = [format stringFromDate:logMessage.date];
}
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;
}
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可是Apple从iOS 10开始，为了减弱ASL对于日志系统的侵入性，直接废弃掉了ASLlink，致使在iOS 10以后的系统版本中没法使用 ASL相关的API。所以为了可以在iOS 10以后的版本中一样获取日志数据，咱们寻找一种版本兼容的解决方案。 2、重定向 一、文件重定向 利用c语言的 freopen 函数进行重定向，将写往 stderr 的内容重定向到咱们制定的文件中去，一旦执行了上述代码那么在这个以后的NSLog将不会在控制台显示了，会直接输出在指定的文件中。xcode
// 最简单的重定向
NSString *filePath = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES).firstObject;
filePath = [filePath stringByAppendingPathComponent:[AutoTestEngine defaultEngine].uuid];
NSString *loggingPath = [filePath stringByAppendingPathComponent:@"result.log"];
//redirect NSLog
freopen([loggingPath cStringUsingEncoding:NSASCIIStringEncoding], "a+", stderr);
freopen([loggingPath cStringUsingEncoding:NSASCIIStringEncoding], "a+", stdout);
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二、dup2 重定向 经过 NSPipe 建立一个管道，pipe有读端和写端，而后经过 dup2 将标准输入重定向到pipe的写端。再通 过 NSFileHandle 监听pipe的读端，最后再处理读出的信息。 以后经过 printf 或者 NSLog 写数据，都会写到pipe的写端，同时pipe会将这些数据直接传送到读端，最后经过NSFileHandle的监控函数取出这些数据，这时能够随意处理，将这些数据写入指定文件。缓存
- (void)redirectStandardOutput{
//记录标准输出及错误流原始文件描述符
outFd = dup(STDOUT_FILENO);
errFd = dup(STDERR_FILENO);
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];
@autoreleasepool {
CFRunLoopRun();
}
}
-(void)recoverStandardOutput{
if (!outFd) {
return;
}
// 恢复至原来路径
dup2(outFd, STDOUT_FILENO);
dup2(errFd, STDERR_FILENO);
[[NSNotificationCenter defaultCenter] removeObserver:self];
}
// 重定向以后的NSLog输出
- (void)redirectOutNotificationHandle:(NSNotification *)nf
{
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现
if (str) {
[self writefile:str];
[[nf object] readInBackgroundAndNotify];
}
}
// 重定向以后的错误输出
- (void)redirectErrNotificationHandle:(NSNotification *)nf
{
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现
if (str) {
[self writefile:str];
[[nf object] readInBackgroundAndNotify];
}
}
- (void)writefile:(NSString *)string
{
NSString *filePath = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES).firstObject;
filePath = [filePath stringByAppendingPathComponent:[AutoTestEngine defaultEngine].uuid];
filePath = [filePath stringByAppendingPathComponent:@"result.log"];
if (![[NSFileManager defaultManager] fileExistsAtPath:filePath]) {
[@"" writeToFile:filePath atomically:YES encoding:NSUTF8StringEncoding error:nil];
}
NSFileHandle *fileHandle = [NSFileHandle fileHandleForUpdatingAtPath:filePath];
[fileHandle seekToEndOfFile]; //将节点跳到文件的末尾
NSData* stringData = [string dataUsingEncoding:NSUTF8StringEncoding];
[fileHandle writeData:stringData]; //追加写入数据
[fileHandle closeFile];
}
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三、dispatch_source_t 重定向app
- (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
NSMutableData* data = [[NSMutableData alloc] init];
fcntl(fd, F_SETFL, O_NONBLOCK);
dispatch_source_t source = dispatch_source_create(DISPATCH_SOURCE_TYPE_READ, fd, 0, _queue);
dispatch_source_set_cancel_handler(source, ^{
});
dispatch_source_set_event_handler(source, ^{
@autoreleasepool {
size_t estimatedSize = dispatch_source_get_data(source) + 1;
char *buffer = (char *)malloc(estimatedSize);
if (buffer) {
ssize_t actual = read(fd, buffer, (estimatedSize));
// do something with buffer
[data appendBytes:buffer length:actual];
NSString *aString = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
NSLog(@"aString = %@",aString);
[self writefile:aString];
free(buffer);
[data resetBytesInRange:NSMakeRange(0, data.length)];
[data setLength:0];
//读取完毕后
// dispatch_source_cancel(source);
}
}
});
dispatch_resume(source);
return source;
}
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在短视频应用中，上面3种重定向方式均有问题，多是短视频app的特殊性，方案1中在app中不生效，方案2在和短视频运行中会致使app卡住，方案3获取到的信息不正确且会卡住，生成文件很大。函数
方案1不生效没法下手，方案2，3尝试解决，查看文档，发现方案2的通知回调必须在消息循环激活中才生效，所以，建立线程，开启消息循环，将监听，读写操做均放在该线程中，解决了同时运行卡住问题，暂时采起方案2来获取app 运行时的输出日志。oop