使用C的库函数获取当前本地时间

1. tm结构体

struct tm {

inttm_sec; /* seconds after the minute [0-60] */
int tm_min;/* minutes after the hour [0-59] */
int tm_hour;/* hours since midnight [0-23] */
int tm_mday;/* day of the month [1-31] */
int tm_mon;/* months since January [0-11] */
int tm_year;/* years since 1900 */
int tm_wday;/* days since Sunday [0-6] */
int tm_yday;/* days since January 1 [0-365] */
int tm_isdst;/* Daylight Savings Time flag */
long tm_gmtoff;/* offset from CUT in seconds */
char *tm_zone;/* timezone abbreviation */

};

2. 使用localtime获取本地时间，具体代码如下

//获取当前时间，采用C的库函数，返回值不需要外部释放，效率方面比使用OC的NSDate类高效3-4倍
- (struct tm*)getTime
{
    //时间格式
    struct timeval ticks;
    gettimeofday(&ticks, nil);
    time_t now;
    struct tm* timeNow;
    time(&now);
    timeNow = localtime(&now);
    timeNow->tm_gmtoff = ticks.tv_usec/1000;  //毫秒
    
    timeNow->tm_year += 1900;    //tm中的tm_year是从1900至今数
    timeNow->tm_mon  += 1;       //tm_mon范围是0-11
   
    return timeNow;
}