iOS nsdate

//获取时间

    NSDate *mydate=[NSDate date];

//创建时间格式

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

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

//得到正确格式的时间

    NSString *realdate=[mydateFormatter stringFromDate:mydate];

    NSLog(@"%@",realdate);

//string转成date

    NSString *myDatestring=@"2014-05-09:10:23:24:100";

    NSDate *mydatenow=[mydateFormatter dateFromString:myDatestring];

//转化成当前所在时区

    NSDate *lastdateNow=[mydatenow dateByAddingTimeInterval:[[NSTimeZone systemTimeZone]secondsFromGMT]];

    NSLog(@"%@",lastdateNow);

    //计算时间戳

    NSTimeInterval timestmp=[mydate timeIntervalSince1970];

    NSLog(@"%.0lf",timestmp);

//通过时间戳得到当前时间

    NSDate *dateFromStmp=[NSDate dateWithTimeIntervalSince1970:timestmp];

//转化成当前所在时区

    NSDate *mydateFromstmmp=[dateFromStmp dateByAddingTimeInterval:[[NSTimeZone systemTimeZone]secondsFromGMT]];

    NSLog(@"%@",mydateFromstmmp);