OC中关于日期与时间的处理
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 stringFromDate: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;}@end