获取时间
NSDate *date = [NSDate date];// 创建时间对象，获得当前时间
NSLog(@"%@", date);//打印出的时间是0 时区的时间（格林威治时间）（北京属于东8区）
转换为本地时间
// 创建一个当前的时间
NSDate *date = [NSDate date];
NSTimeZone *zone = [NSTimeZone systemTimeZone];
// 获取时间间隔
NSTimeInterval interval = [zone secondsFromGMTForDate:date];
// 东八区时间
NSDate *locaDate = [date dateByAddingTimeInterval:interval];
NSLog(@"%@", locaDate)
当前时间---->时间戳
@interface NSDate (NSExtendedDate)
- (NSTimeInterval)timeIntervalSinceDate:(NSDate *)anotherDate;
@property (readonly) NSTimeInterval timeIntervalSinceNow;
@property (readonly) NSTimeInterval timeIntervalSince1970;
1.首先获取0时区的时间转成东八区的时间
// 创建一个当前的时间
NSDate *date = [NSDate date];
NSTimeZone *zone = [NSTimeZone systemTimeZone];
// 获取时间间隔
NSTimeInterval interval = [zone secondsFromGMTForDate:date];
// 东八区时间
NSDate *locaDate = [date dateByAddingTimeInterval:interval];
NSLog(@"%@", locaDate)
2.将获得的东八区时间转换成时间戳
// 获得时间戳
// 获得时间戳
NSTimeInterval interval1 = [locaDate timeIntervalSince1970]; // 距离1970
NSTimeInterval inveral2 = [locaDate timeIntervalSinceNow]; // 当前时间
NSLog(@"%f", interval1);
答应时间戳: 2016-06-08 13:52:59.845 test[14109:3160430] 1465393979.843557
时间戳------>时间
@interface NSDate (NSDateCreation)
+ (instancetype)date;
+ (instancetype)dateWithTimeIntervalSinceNow:(NSTimeInterval)secs;
+ (instancetype)dateWithTimeIntervalSinceReferenceDate:(NSTimeInterval)ti;
+ (instancetype)dateWithTimeIntervalSince1970:(NSTimeInterval)secs;
+ (instancetype)dateWithTimeInterval:(NSTimeInterval)secsToBeAdded sinceDate:(NSDate *)date;
案例
NSDate *date = [NSDate dateWithTimeIntervalSinceNow:28799.998401];
NSLog(@"%@", date);
时间的格式
注意:这里不需要将获取的时间转换时区
date转成日期格式的字符串
// NSDate -->NSString
NSDate *date = [NSDate date];
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
formatter.dateFormat = @"yyyy-MM-dd HH:mm:ss";
NSString *timeString = [formatter stringFromDate:date];
NSLog(@"%@", timeString); 东八区时间字符串
将日期格式的字符串转换成Date
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
formatter.dateFormat = @"yyyy-MM-dd HH:mm:ss";//日期格式化类
NSString *string = @"2015-4-16 16:42:31";//设置时间格式
// 注意这里获取打印的时间是0时区的date 2015-04-16 08:42:31 +0000
// 转换成东八区时间
NSDate *date = [formatter dateFromString:string];//转化为NSDate时间
NSTimeZone *zone = [NSTimeZone systemTimeZone];
NSInteger seconds = [zone secondsFromGMTForDate:date];
NSDate *date8 = [date dateByAddingTimeInterval:seconds];
NSLog(@"%@", date8); // 打印结果 2015-04-16 16:42:31 +00
NSDate常用的一些属性 方法
时间间隔
NSDate *date = [NSDate date];
NSDate *date2 = [NSDate dateWithTimeInterval : 5 sinceDate:date]; // 与当前时间相隔5秒
NSTimeInterval seconds = [date timeIntervalSince1970]//从1970年到现在的秒数
//从现在开始的24小时
NSTimeInterval secondsPerDay = 24*60*60;
NSDate *tomorrow = [NSDate dateWithTimeIntervalSinceNow:secondsPerDay];
NSLog(@"tomorrow = %@",tomorrow);
//根据已有日期创建日期
NSTimeInterval secondsPerDay1 = 24*60*60;
NSDate *now = [NSDate date];
NSDate *yesterDay = [now dateByAddingTimeInterval:-secondsPerDay1];
NSLog(@"yesterDay = %@",yesterDay);
比较时间
//比较日期
BOOL sameDate = [now isEqualToDate:yesterDay];
NSLog(@"sameDate = %hhd",sameDate);
//获取较早的日期
NSDate *earlierDate = [yesterDay earlierDate:now];
NSLog(@"earlierDate = %@",earlierDate);
//获取较晚的日期
NSDate *laterDate = [yesterDay laterDate:now];
NSLog(@"laterDate = %@",laterDate);
//两个日期之间相隔多少秒
NSTimeInterval secondsBetweenDates= [yesterDay timeIntervalSinceDate:now];
NSLog(@"secondsBetweenDates= %lf",secondsBetweenDates);
通过日历来创建时间
//通过NSCalendar类来创建日期
NSDateComponents *comp = [[NSDateComponents alloc]init];
[comp setMonth:06];
[comp setDay:12];
[comp setYear:2015];
NSCalendar *myCal= [[NSCalendar alloc]initWithCalendarIdentifier:NSCalendarIdentifierGregorian];
NSDate *myDate1 = [myCal dateFromComponents:comp];
NSLog(@"myDate1 = %@",myDate1);
//从已有日期获取日期
unsigned units = NSCalendarUnitMonth|NSCalendarUnitDay|NSCalendarUnitYear;
NSDateComponents *comp1 = [myCal components:units fromDate:now];
NSInteger month = [comp1 month];
NSInteger year = [comp1 year];
NSInteger day = [comp1 day];
//NSDateFormatter实现日期的输出
NSDateFormatter *formatter = [[NSDateFormatter alloc]init];
[formatter setDateStyle:NSDateFormatterFullStyle];//直接输出的话是机器码
//或者是手动设置样式[formatter setDateFormat:@"yyyy-mm-dd"];
NSString *string = [formatter stringFromDate:now];
NSLog(@"string = %@",string);
NSLog(@"formater = %@",formatter);
//用NSCalendar实现，计算某个时间C是某个日期B是相应时期A，中的第几(Hour?Day?Month?)
NSCalendar *cal = [NSCalendar currentCalendar];
NSLog(@"My calendar is %@",[cal calendarIdentifier]);//获取日期格式对象
unsigned long daymonth = [cal ordinalityOfUnit:NSCalendarUnitDay//时间B(天)
inUnit:NSCalendarUnitMonth//时间A(月)
forDate:now];//时间C(当前时间)
NSLog(@"This is day %lu of the month",daymonth);//当前时间C，是一个月(A)的第几天(B)
