获取当前系统时间的时间戳

+(NSInteger)getNowTimestamp{
    NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
    [formatter setDateStyle:NSDateFormatterMediumStyle];
    [formatter setTimeStyle:NSDateFormatterShortStyle];
    [formatter setDateFormat:@"YYYY-MM-dd HH:mm:ss"]; // ----------设置你想要的格式,hh与HH的区别:分别表示12小时制,24小时制
    //设置时区,这个对于时间的处理有时很重要
    NSTimeZone* timeZone = [NSTimeZone timeZoneWithName:@"Asia/Beijing"];
    [formatter setTimeZone:timeZone];
    NSDate *datenow = [NSDate date];//现在时间
    NSLog(@"设备当前的时间:%@",[formatter stringFromDate:datenow]);
    //时间转时间戳的方法:
    NSInteger timeSp = [[NSNumber numberWithDouble:[datenow timeIntervalSince1970]] integerValue];
    NSLog(@"设备当前的时间戳:%ld",(long)timeSp); //时间戳的值
    return timeSp;
}

将某个时间转化成 时间戳

+(NSInteger)timeSwitchTimestamp:(NSString *)formatTime andFormatter:(NSString *)format{
    NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
    [formatter setDateStyle:NSDateFormatterMediumStyle];
    [formatter setTimeStyle:NSDateFormatterShortStyle];
    [formatter setDateFormat:format]; //(@"YYYY-MM-dd hh:mm:ss") ----------设置你想要的格式,hh与HH的区别:分别表示12小时制,24小时制
    NSTimeZone* timeZone = [NSTimeZone timeZoneWithName:@"Asia/Beijing"];
    [formatter setTimeZone:timeZone];
    NSDate* date = [formatter dateFromString:formatTime]; //------------将字符串按formatter转成nsdate
    //时间转时间戳的方法:
    NSInteger timeSp = [[NSNumber numberWithDouble:[date timeIntervalSince1970]] integerValue];
    NSLog(@"将某个时间转化成 时间戳&&&&&&&timeSp:%ld",(long)timeSp); //时间戳的值
    return timeSp;

}
```

####将某个时间戳转化成 时间
```
+(NSString *)timestampSwitchTime:(NSInteger)timestamp andFormatter:(NSString *)format{
    NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
    [formatter setDateStyle:NSDateFormatterMediumStyle];
    [formatter setTimeStyle:NSDateFormatterShortStyle];
    [formatter setDateFormat:format]; // （@"YYYY-MM-dd hh:mm:ss"）----------设置你想要的格式,hh与HH的区别:分别表示12小时制,24小时制
    NSTimeZone *timeZone = [NSTimeZone timeZoneWithName:@"Asia/Beijing"];
    [formatter setTimeZone:timeZone];
    NSDate *confromTimesp = [NSDate dateWithTimeIntervalSince1970:timestamp];
    NSLog(@"1296035591  = %@",confromTimesp);
    NSString *confromTimespStr = [formatter stringFromDate:confromTimesp];
    //NSLog(@"&&&&&&&confromTimespStr = : %@",confromTimespStr);
    return confromTimespStr;
}
```