iOS - NSLog、UncaughtException日志保存到文件

对于真机，日志没法保存，不好分析问题。所以有必要将日志保存到应用的Docunment目录下，方便取出分析。

首先是日志输出，分为c的printf和标准的NSLog输出，printf会向标准输出(sedout)打印，而NSLog则是向标准出错(stderr)，我们需要同时让他们都将日志打印到一个文件中。 其次是Crash问题；Crash分为两种，一种是由EXC_BAD_ACCESS引起的，原因是访问了不属于本进程的内存地址，有可能是访问已被释放的内存；另一种是未被捕获的Objective-C异常（NSException），导致程序向自身发送了SIGABRT信号而崩溃。其实对于未捕获的Objective-C异常，我们是有办法将它记录下来的，如果日志记录得当，能够解决绝大部分崩溃的问题。

我写了两个函数用于写NSLog日志和Crash日志，这个两个函数都必须在AppDelegate文件中下面的函数里添加

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions

    //连接xcode时可以从监视器中看日志 没连接时Log日志会输出到文件中，    [self redirectNSLogToDocumentFolder];

- (void)redirectNSLogToDocumentFolder{    //如果已经连接Xcode调试则不输出到文件    if(isatty(STDOUT_FILENO)) {        return;    }        UIDevice *device = [UIDevice currentDevice];    if([[device model] hasSuffix:@"Simulator"]){ //在模拟器不保存到文件中        return;    }        //将NSlog打印信息保存到Document目录下的Log文件夹下    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);    NSString *logDirectory = [[paths objectAtIndex:0] stringByAppendingPathComponent:@"Log"];        NSFileManager *fileManager = [NSFileManager defaultManager];BOOL fileExists = [fileManager fileExistsAtPath:logDirectory];    if (!fileExists) {[fileManager createDirectoryAtPath:logDirectory  withIntermediateDirectories:YES attributes:nil error:nil];}        NSDateFormatter *formatter = [[NSDateFormatter alloc] init];    [formatter setLocale:[[NSLocale alloc] initWithLocaleIdentifier:@"zh_CN"]];    [formatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"]; //每次启动后都保存一个新的日志文件中    NSString *dateStr = [formatter stringFromDate:[NSDate date]];    NSString *logFilePath = [logDirectory stringByAppendingFormat:@"/%@.log",dateStr];        // 将log输入到文件    freopen([logFilePath cStringUsingEncoding:NSASCIIStringEncoding], "a+", stdout);    freopen([logFilePath cStringUsingEncoding:NSASCIIStringEncoding], "a+", stderr);        //未捕获的Objective-C异常日志    NSSetUncaughtExceptionHandler (&UncaughtExceptionHandler);}void UncaughtExceptionHandler(NSException* exception){    NSString* name = [ exception name ];    NSString* reason = [ exception reason ];    NSArray* symbols = [ exception callStackSymbols ]; // 异常发生时的调用栈    NSMutableString* strSymbols = [ [ NSMutableString alloc ] init ]; //将调用栈拼成输出日志的字符串    for ( NSString* item in symbols )    {        [ strSymbols appendString: item ];        [ strSymbols appendString: @"\r\n" ];    }        //将crash日志保存到Document目录下的Log文件夹下    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);    NSString *logDirectory = [[paths objectAtIndex:0] stringByAppendingPathComponent:@"Log"];        NSFileManager *fileManager = [NSFileManager defaultManager];    if (![fileManager fileExistsAtPath:logDirectory]) {[fileManager createDirectoryAtPath:logDirectory  withIntermediateDirectories:YES attributes:nil error:nil];}        NSString *logFilePath = [logDirectory stringByAppendingPathComponent:@"UncaughtException.log"];    NSDateFormatter *formatter = [[NSDateFormatter alloc] init];    [formatter setLocale:[[NSLocale alloc] initWithLocaleIdentifier:@"zh_CN"]];    [formatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"];    NSString *dateStr = [formatter stringFromDate:[NSDate date]];        NSString *crashString = [NSString stringWithFormat:@"<- %@ ->[ Uncaught Exception ]\r\nName: %@, Reason: %@\r\n[ Fe Symbols Start ]\r\n%@[ Fe Symbols End ]\r\n\r\n", dateStr, name, reason, strSymbols];    //把错误日志写到文件中    if (![fileManager fileExistsAtPath:logFilePath]) {        [crashString writeToFile:logFilePath atomically:YES encoding:NSUTF8StringEncoding error:nil];    }else{        NSFileHandle *outFile = [NSFileHandle fileHandleForWritingAtPath:logFilePath];        [outFile seekToEndOfFile];        [outFile writeData:[crashString dataUsingEncoding:NSUTF8StringEncoding]];        [outFile closeFile];    }        //把错误日志发送到邮箱    //    NSString *urlStr = [NSString stringWithFormat:@"mailto://[e-mail]?subject=bug报告&body=感谢您的配合!<br><br><br>错误详情:<br>%@",crashString ];    //    NSURL *url = [NSURL URLWithString:[urlStr stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];    //    [[UIApplication sharedApplication] openURL:url];}