在我们的开发中与日期打交道是常有的事情,OC中提供了NSDate和NSCalendar来给我们进行时间相关的处理与操作,还是非常容易的,下面我们就一起看一看.
1.NSDate基本概念
NSDate可以用来表示时间, 可以进行一些常见的日期\时间处理,一个NSDate对象就代表一个时间
获取系统当前时间
NSDate *now = [NSDate date];获取系统当前时间戳
NSTimeInterval nowTimestamp = [[NSDate date] timeIntervalSince1970] * 1000.0;计算时间间隔
NSDate *myDate = [now timeIntervalSinceDate:otherDate];
NSDate *now = [NSDate date];
NSLog(@"now = %@", now);
// 设置转换后的目标日期时区
NSTimeZone *zone = [NSTimeZone systemTimeZone];
// 得到源日期与世界标准时间的偏移量
NSInteger interval = [zone secondsFromGMTForDate: date];
NSLog(@"interval = %lu", interval);
// 在当前时间基础上追加时区差值
now = [now dateByAddingTimeInterval:interval];
NSLog(@"%@", date);2.格式化日期
NSDate -> NSString
// 1.创建时间
NSDate *now = [NSDate date];
// 2.创建时间格式化
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
// 3.指定格式
formatter.dateFormat = @"yyyy-MM-dd HH:mm:ss";
// 4.格式化时间
NSString *str = [formatter stringFromDate:now];
NSLog(@"%@", str);NSString -> NSDate
NSString *str = @"2015-06-28 19:53:24";
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
formatter.dateFormat = @"yyyy-MM-dd HH:mm:ss";
NSDate *date = [formatter dateFromString:str];
NSLog(@"%@", date);解析 欧美格式 日期字符串
- (void)fmt_string_to_date2{
// 服务器返回的时间字符串
NSString *string = @"Tue May 31 17:46:55 +0800 2011";
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
formatter.dateFormat = @"EEE MMM dd HH:mm:ss ZZZZ yyyy";
NSDate * date = [formatter dateFromString:string];
NSLog(@"%@", date);
}timestamp -> NSDate
// 解析 时间戳
- (void)fmt_string_to_date3{
// 时间戳: 从1970年1月1日开始经历的毫秒数
NSInteger timestamp = 1445164401875.157959;
// 获取系统当前的时间戳
// NSTimeInterval nowTimestamp = [[NSDate date] timeIntervalSince1970] * 1000.0;
NSDate *date = [NSDate dateWithTimeIntervalSince1970:timestamp/1000.0];
NSLog(@"%@", date);
}3.日期时间对象
结合NSCalendar和NSDate能做更多的 日期\时间 处理
获得NSCalendar对象
NSCalendar *calendar = [NSCalendar currentCalendar];获得年月日
- (NSDateComponents *)components:(NSCalendarUnit)unitFlags fromDate:(NSDate *)date;
NSDate *date = [NSDate date];
// 1.创建日历对象
NSCalendar *calendar = [NSCalendar currentCalendar];
// 2.利用日历对象获取年月日时分秒
NSCalendarUnit unit = NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay | NSCalendarUnitHour | NSCalendarUnitMinute | NSCalendarUnitSecond;
NSDateComponents *components =[calendar components:type fromDate:date];
NSLog(@"year = %lu", cmps.year);
NSLog(@"month = %lu", cmps.month);
NSLog(@"day = %lu", cmps.day);
NSLog(@"hour = %lu", cmps.hour);
NSLog(@"minute = %lu", cmps.minute);
NSLog(@"second = %lu", cmps.second);
NSLog(@"date = %@", date);比较两个日期的差距
- (NSDateComponents *)components:(NSCalendarUnit)unitFlags fromDate:(NSDate *)startingDate toDate:(NSDate *)resultDate options:(NSCalendarOptions)opts;
// 1.确定时间
NSString *time1 = @"2015-06-23 12:18:15";
NSString *time2 = @"2015-06-28 10:10:10";
// 2.将时间转换为date
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
formatter.dateFormat = @"yyyy-MM-dd HH:mm:ss";
NSDate *date1 = [formatter dateFromString:time1];
NSDate *date2 = [formatter dateFromString:time2];
// 3.创建日历
NSCalendar *calendar = [NSCalendar currentCalendar];
NSCalendarUnit unit = NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay | NSCalendarUnitHour | NSCalendarUnitMinute | NSCalendarUnitSecond;
// 4.利用日历对象比较两个时间的差值
NSDateComponents *cmps = [calendar components:unit fromDate:date1 toDate:date2 options:0];
// 5.输出结果
NSLog(@"两个时间相差%ld年%ld月%ld日%ld小时%ld分钟%ld秒", cmps.year, cmps.month, cmps.day, cmps.hour, cmps.minute, cmps.second);iOS8.0开始,NSCalendar增加了一些更为简单的判断日期的方法,如:
- (BOOL)isDate:(NSDate *)date1 equalToDate:(NSDate *)date2 toUnitGranularity:(NSCalendarUnit)unit;
- (BOOL)isDate:(NSDate *)date1 inSameDayAsDate:(NSDate *)date2;
- (BOOL)isDateInToday:(NSDate *)date;
- (BOOL)isDateInYesterday:(NSDate *)date;
- (BOOL)isDateInTomorrow:(NSDate *)date;
- (BOOL)isDateInWeekend:(NSDate *)date;但是iOS8.0以前是没有这些方法的,为了更好的兼容iOS8.0以前的项目,我们可以人为的给NSDate类做一些扩展.(新建继承自NSDate的分类,在分类里扩展方法)
代码如下所示:
#import "NSDate+BSExtension.h"
@implementation NSDate (BSExtension)
/**
* 是否是今天
*/
- (BOOL)isToday{
NSCalendar *calendar = [NSCalendar currentCalendar];
NSCalendarUnit unit = NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay;
// 获取时间
NSDateComponents *selfCmps = [calendar components:unit fromDate:self];
NSDateComponents *nowCmps = [calendar components:unit fromDate:[NSDate date]];
return selfCmps.year == nowCmps.year && selfCmps.month == nowCmps.month && selfCmps.day == nowCmps.day;
}
/**
* 是否是昨天
*/
- (BOOL)isYesterday{
// 生成只有年月日的日期对象
NSDateFormatter *fmt = [[NSDateFormatter alloc] init];
fmt.dateFormat = @"yyyy-MM-dd";
NSString *selfString = [fmt stringFromDate:self];
NSDate *selfDate = [fmt dateFromString:selfString];
NSString *nowString = [fmt stringFromDate:[NSDate date]];
NSDate *nowDate = [fmt dateFromString:nowString];
// 比较时间差
NSCalendar *calendar = [NSCalendar currentCalendar];
NSCalendarUnit unit = NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay;
NSDateComponents *cmps = [calendar components:unit fromDate:selfDate toDate:nowDate options:0];
return cmps.year == 0 && cmps.month == 0 && cmps.day == 1;
}
/**
* 是否是明天
*/
- (BOOL)isTomorrow{
// 生成只有年月日的日期对象
NSDateFormatter *fmt = [[NSDateFormatter alloc] init];
fmt.dateFormat = @"yyyy-MM-dd";
NSString *selfString = [fmt stringFromDate:self];
NSDate *selfDate = [fmt dateFromString:selfString];
NSString *nowString = [fmt stringFromDate:[NSDate date]];
NSDate *nowDate = [fmt dateFromString:nowString];
// 比较时间差
NSCalendar *calendar = [NSCalendar currentCalendar];
NSCalendarUnit unit = NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay;
NSDateComponents *cmps = [calendar components:unit fromDate:selfDate toDate:nowDate options:0];
return cmps.year == 0 && cmps.month == 0 && cmps.day == -1;
}
/**
* 是否是今年
*/
- (BOOL)isThisYear{
NSCalendar *calendar = [NSCalendar currentCalendar];
NSInteger selfYear = [calendar component:NSCalendarUnitYear fromDate:self];
NSInteger nowYear = [calendar component:NSCalendarUnitYear fromDate:[NSDate date]];
return selfYear == nowYear;
}
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