//        //  main.m        //  OC05-task-06        //        //  Created by Xin the Great on 15-1-26.        //  Copyright (c) 2015年 Xin the Great. All rights reserved.        //                #import <Foundation/Foundation.h>                int main(int argc, const charchar * argv[]) {            @autoreleasepool {                // insert code here...                //////////////////////NSDate --- 日期//////////////////////                                //获取当前系统的时间   标准时间 GMT  格林尼治时间                NSDate *date = [NSDate date];                NSLog(@"date is %@", date);                                NSDate *date1 = [[NSDate alloc] init];                NSLog(@"date1 is %@", date1);                                //获取时间戳   以秒为单位                NSTimeInterval time1970 = [date timeIntervalSince1970];                NSLog(@"time1970 is %.1f", time1970);                                NSTimeInterval time2001 = [date timeIntervalSinceReferenceDate];                NSLog(@"time2001 is %.1f", time2001);                                NSTimeInterval time = [date timeIntervalSinceNow];                NSLog(@"time is %.1f", time);                                //获取昨天的时间                NSTimeInterval second = 224 * 660 * 60;                NSDate *yesterDayDate = [[NSDate alloc] initWithTimeIntervalSinceNow:-second];                NSLog(@"yesterDayDate is %@",yesterDayDate);                                //获取明天的时间                NSDate *tomorrowDayDate = [NSDate dateWithTimeInterval:second sinceDate:[NSDate date]];                NSLog(@"tomorrowDayDate is %@", tomorrowDayDate);                                //获得未来的某一个时间                NSDate *future = [NSDate distantFuture];                NSLog(@"future is %@", future);                                //获得古代的某一个时间                NSDate *past = [NSDate distantPast];                NSLog(@"past is %@", past);                                //日期的比较        //        BOOL isTure = [date isEqualToDate:date1];        //        NSLog(@"isTure is %d", isTure);                                //返回两个时间比较早的那个时间                NSDate *earlierDate = [tomorrowDayDate earlierDate:future];                NSLog(@"earlierDate is %@", earlierDate);                                //返回两个时间比较晚的那个时间                NSDate *later = [tomorrowDayDate laterDate:future];                NSLog(@"later is %@", later);                                                //将时间戳转换成字符串                NSString *str = @"123456789";                NSTimeInterval second2 = [str doubleValue];                NSDate *date3 = [NSDate dateWithTimeIntervalSince1970:second2];                NSLog(@"date3 is %@", date3);                                //格式化日期类                NSDateFormatter *df = [[NSDateFormatter alloc] init];                [df setDateFormat:@"yyyy年MM月dd日 HH小时mm分钟ss秒 ZZZZ"];                                //将日期按照格式化日期类转换为字符串                NSString *str2 = [df stringFromDate:date3];                NSLog(@"str2 is %@", str2);                                //通过字符串转换为date                NSDate *date4 = [df dateFromString:str2];                NSLog(@"date4 is %@", date4);                            }            return 0;        }