格式化时间，如忽略秒

getDateByFormat

+ (NSDate*)_getDateBySecondFormat:(NSDate*)date
{
    return [self _getDateByFormat:date
                           Format:@"yyyy/MM/dd HH:mm"];
}

+ (NSDate*)_getDateByFormat:(NSDate*)date Format:(NSString*)format
{
    NSDateFormatter* formatter = [[NSDateFormatter alloc] init];
    [formatter setDateFormat:format];
    NSString *dateStr = [formatter stringFromDate:date];
    return [formatter dateFromString: dateStr];
}