IOS 生成csv

+ (NSMutableArray *)transferByArray:(NSMutableArray *)specList {
    NSInteger space = specList.count/401;
    NSMutableArray *newList = [NSMutableArray array];
    
    // 写csv
    NSString *path = [YXG_FileTools pathByFileName:@"yxg401.csv" path:[YXG_FileTools pathByDirectoryName:@"yangxuguang003"]];
    NSOutputStream *output = [[NSOutputStream alloc] initToFileAtPath:path append:YES];
    [output open];
    if (![output hasSpaceAvailable]) {
        NSLog(@"❌没有空间");
    }
    NSInteger result = 0;
    for (NSInteger i = 0; i < 401; i ++) {
        float value = [specList[i*space] floatValue];
        [newList addObject:@(value)];
        
        // 写入csv
        NSString *string = [NSString stringWithFormat:@"%ld,%@\n",380+i,specList[i*space]];
        uint8_t buffer[2048];
        memcpy(buffer, [string UTF8String], [string length]+1);
        result = [output write:buffer maxLength: [string length]];
    }
    [output close];
    return newList;
}