将日志非覆盖式的写入沙盒mylog.log文件中

//将日志写入沙盒mylog.log文件中
-(void)writeLogMessageToLocationFile:(NSString *)logMessagesString isCover:(BOOL)isCover{

    // NSDocumentDirectory 要查找的文件
    // NSUserDomainMask 代表从用户文件夹下找
    // 在iOS中，只有一个目录跟传入的参数匹配，所以这个集合里面只有一个元素
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsPath = [paths objectAtIndex:0];
    NSString *loggingPath = [documentsPath stringByAppendingPathComponent:@"/mylog.log"];
    NSLog(@"%@",loggingPath);

    //覆盖文件的原先内容
    if(isCover == YES) {
        [logMessagesString writeToFile:loggingPath atomically:YES encoding:NSUTF8StringEncoding error:nil];

    }
    else {
        NSFileManager *fileManger = [NSFileManager defaultManager];
        if (![fileManger fileExistsAtPath:loggingPath]) {
            [logMessagesString writeToFile:loggingPath atomically:YES encoding:NSUTF8StringEncoding error:nil];
        }
        NSFileHandle *fileHandle = [NSFileHandle fileHandleForUpdatingAtPath:loggingPath];
        [fileHandle seekToEndOfFile];  //将节点跳到文件的末尾

        NSData* stringData  = [logMessagesString dataUsingEncoding:NSUTF8StringEncoding];

        [fileHandle writeData:stringData]; //追加写入数据

        [fileHandle closeFile];

    }

}