字符串和时间戳相互转换

+(NSInteger)timeStampWithString:(NSString *)timeStr{

    NSDateFormatter *formatter = [[NSDateFormatter alloc]init];

    [formatter setDateFormat:@"yyyy-MM-dd"];

    NSDate *date = [formatter dateFromString:timeStr];

    NSInteger time = [date timeIntervalSince1970];

    NSLog(@"aaaaaa----%lld",(long long)time);

    return time;

}

+(NSString *)stringWithTimeStamp:(NSInteger)timeStamp{

    NSDate *dateStamp = [NSDate dateWithTimeIntervalSince1970:timeStamp];

    NSDateFormatter *formatter = [[NSDateFormatter alloc]init];

    [formatter setDateFormat:@"yyyy-MM-dd"];

    NSString *birthday = [formatter stringFromDate:dateStamp];

    NSLog(@"22222222-----%@",birthday);

    return birthday;

}