NSDate、NSString、long转化

- (NSDate *)dateFromString:(NSString *)dateString{

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

    [dateFormatter setDateFormat: @"yyyy-MM-dd HH:mm:ss"];

    NSDate *destDate= [dateFormatter dateFromString:dateString];

    return destDate;

}

- (NSString *)stringFromDate:(NSDate *)date{

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

    //zzz表示时区，zzz可以删除，这样返回的日期字符将不包含时区信息。

    [dateFormatter setDateFormat:@"MM-dd HH:mm"];

    NSString *destDateString = [dateFormatter stringFromDate:date];

    return destDateString;

}

-(NSString *)stringFromValue:(NSString *)value{

    NSDate *confromTimesp = [NSDate dateWithTimeIntervalSince1970:[value longLongValue]];

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

    [formatter setDateFormat:@"MM-dd HH:mm"];

    NSString *date = [formatter stringFromDate:confromTimesp];

    return date;

}