#import <Foundation/Foundation.h>

int main(int argc, const char * argv[])

{

    @autoreleasepool {

        NSDate *date = [NSDate date];

        NSLog(@"date = %@",date);

        //距离现在时间多少s之后的时间

        NSDate *date2 = [NSDate dateWithTimeIntervalSinceNow:];

        NSLog(@"date2 = %@",date2);

        //时间戳:距离1970/01/01 00:00:00之后的秒数

        //距离1970/01/01 这个时间点100s之后的时间

        NSDate *date3 = [NSDate dateWithTimeIntervalSince1970:];

        NSLog(@"date3 = %@",date3);

        //距离date3之后100s的时间

        NSDate *date4 = [NSDate dateWithTimeInterval: sinceDate:date3];

        NSLog(@"date4 = %@",date4);

        //遥远的未来

        NSDate *date5 = [NSDate distantFuture];

        NSLog(@"date5 = %@",date5);

        //遥远的过去

        NSDate *date6 = [NSDate distantPast];

        NSLog(@"date6 = %@",date6);

        NSDate *date7 = [NSDate date];

        //返回以当前时间为基准，然后过了1000秒的时间

        NSDate *date8 = [NSDate dateWithTimeIntervalSinceNow:];

        //以date7为基准时间，返回实例保存的时间与date7的时间间隔

        double time = [date8 timeIntervalSinceDate:date7];

        NSLog(@"time = %f",time);

        //返回以当前NSDate对象为基准，偏移1000秒后得到的新NSDate对象

        NSDate *date9 = [date8 dateByAddingTimeInterval:];

        NSLog(@"date7--date9 = %@--%@",date7,date9);

        //与date9比较，返回较早的那个日期

        NSDate *date10 = [date7 earlierDate:date9];

        //与date9比较，返回较晚的那个日期

        NSDate *date11 = [date7 laterDate:date9];

        NSLog(@"date10--date11 = %@--%@",date10,date11);

        NSDate *dateNow = [NSDate date];

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

        //设置格式

        df.dateFormat = @"yyyy-MM-dd HH:mm:ss";

        //NSDate转NSString

        NSString *dateTime = [df stringFromDate:dateNow];

        NSLog(@"dateTime = %@",dateTime);

        NSString *dateStr = @"2015-03-10 00:00:00";

        //NSString转NSDate

        NSDate *date12 = [df dateFromString:dateStr];

        NSLog(@"date12 = %@",date12);

    }

    return ;

}