iOS SDK详解之NSCalendar & NSDate​Components

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前言：NSCalendar 和 NSDate​Components是有关iOS 时间相关API很重要的两个类。最近刚好用到，这里就整理下。

概念

• NSCalendar 顾名思义就是日历，封装了系统如何按照年月日的方式来组织时间,组织时间的方式和地区,时区有很大关系
• NSDate​Components 只是一个容器，容器中详细包含了年月日时分等信息。
• NSDate 就是一个绝对的时间，可以换算成相对1970s的时差。

举例

拆分一个时间
OC

  NSDate * date = [NSDate date];//当前时间
    NSCalendar * calendar = [NSCalendar currentCalendar];//当前用户的calendar
    NSDateComponents * components = [calendar components:NSCalendarUnitMinute | NSCalendarUnitMonth | NSCalendarUnitHour | NSCalendarUnitDay fromDate:date];
    NSLog(@"%ld月%ld日%ld时%ld分" ,(long)components.month,(long)components.day,(long)components.hour,(long)components.minute);

Swift

   let date = NSDate()
   let calendar = NSCalendar.currentCalendar()
   let components = calendar.components(NSCalendarUnit.CalendarUnitMonth | NSCalendarUnit.CalendarUnitDay | NSCalendarUnit.CalendarUnitHour | NSCalendarUnit.CalendarUnitMinute, fromDate:date)
   NSLog("%ld月%ld日%ld时%ld分" ,components.month, components.day, components.hour, components.minute)

相对序号
例如，查看今天是在今年的第几周

  NSCalendar * calendar = [NSCalendar currentCalendar];
    NSDate * currentDate = [NSDate date];
    NSInteger week = [calendar ordinalityOfUnit:NSCalendarUnitWeekday inUnit:NSCalendarUnitYear forDate:currentDate];
    NSLog(@"今天是今年的第%ld周",week);

根据拆分时间返回NSDate
OC

 NSDateComponents * components = [[NSDateComponents alloc] init];
    components.year = 2015;
    components.month = 7;
    components.day = 11;
    components.hour = 10;
    components.minute = 30;
    components.second = 20;
    NSCalendar * calendar = [NSCalendar currentCalendar];
    NSDate * date = [calendar dateFromComponents:components];

    NSDateFormatter * formatter = [[NSDateFormatter alloc] init];
    formatter.dateFormat = @"yyyy年MM月dd日hh时mm分ss秒";
    NSString * str = [formatter stringFromDate:date];
    NSLog(@"%@",str);

Swift

  let components = NSDateComponents()
        components.year = 2015
        components.month = 7
        components.day = 11
        components.hour = 10
        components.minute = 30
        components.second = 20
        let calendar = NSCalendar.currentCalendar()
        let date = calendar.dateFromComponents(components)

        let formatter = NSDateFormatter();
        formatter.dateFormat = "yyyy年MM月dd日hh时mm分ss秒";
        let str = formatter.stringFromDate(date!);
        println(str)

相对时间

现在往后11天10小时
OC

 NSDateComponents * components = [[NSDateComponents alloc] init];

    components.day = 11;
    components.hour = 10;
    NSCalendar * calendar = [NSCalendar currentCalendar];
    NSDate * currentDate = [NSDate date];
    NSDate * nextData = [calendar dateByAddingComponents:components toDate:currentDate options:NSCalendarMatchStrictly];
    NSDateFormatter * formatter = [[NSDateFormatter alloc] init];

    formatter.dateFormat = @"yyyy年MM月dd日hh时mm分ss秒";
    NSString * str = [formatter stringFromDate:nextData];
    NSLog(@"%@",str);

Swift

let components = NSDateComponents()

components.day = 11;
components.hour = 10;

let calendar = NSCalendar.currentCalendar();
let currentDate = NSDate()
let nextDate = calendar.dateByAddingComponents(components, toDate: currentDate, options:NSCalendarOptions.MatchStrictly)


let formatter = NSDateFormatter();

formatter.dateFormat = "yyyy年MM月dd日hh时mm分ss秒";
let  str = formatter.stringFromDate(nextDate!)
NSLog("%@",str);

这个月有多少天

 NSCalendar * calendar = [NSCalendar currentCalendar];
    NSDate * currentDate = [NSDate date];
    NSRange range = [calendar rangeOfUnit:NSCalendarUnitDay inUnit:NSCalendarUnitMonth forDate:currentDate];

其他

创建不同地区的NSCalendar

initWithCalendarIdentifier:

其中有效的identifer

NSString * const NSGregorianCalendar;
NSString * const NSBuddhistCalendar;
NSString * const NSChineseCalendar;
NSString * const NSHebrewCalendar;
NSString * const NSIslamicCalendar;
NSString * const NSIslamicCivilCalendar;
NSString * const NSJapaneseCalendar;
NSString * const NSRepublicOfChinaCalendar;
NSString * const NSPersianCalendar;
NSString * const NSIndianCalendar;
NSString * const NSISO8601Calendar;

一周的开始日期

– firstWeekday

时区和地区

locale
timeZone

所有的NSCalendarUnit

 NSEraCalendarUnit = kCFCalendarUnitEra, NSYearCalendarUnit = kCFCalendarUnitYear, NSMonthCalendarUnit = kCFCalendarUnitMonth, NSDayCalendarUnit = kCFCalendarUnitDay, NSHourCalendarUnit = kCFCalendarUnitHour, NSMinuteCalendarUnit = kCFCalendarUnitMinute, NSSecondCalendarUnit = kCFCalendarUnitSecond, NSWeekCalendarUnit = kCFCalendarUnitWeek, NSWeekdayCalendarUnit = kCFCalendarUnitWeekday, NSWeekdayOrdinalCalendarUnit = kCFCalendarUnitWeekdayOrdinal, NSQuarterCalendarUnit = kCFCalendarUnitQuarter, NSWeekOfMonthCalendarUnit = kCFCalendarUnitWeekOfMonth, NSWeekOfYearCalendarUnit = kCFCalendarUnitWeekOfYear, NSYearForWeekOfYearCalendarUnit = kCFCalendarUnitYearForWeekOfYear NSCalendarCalendarUnit = (1 << 20), NSTimeZoneCalendarUnit = (1 << 21),