An article thoroughly understand iOS, JS time and date (date, Calendar, Locale, TimeZone)

iOS time-related classes

• NSDate-Represents an absolute point in time.
• Nscalendar-Represents a specific calendar, such as the Gregorian or Hebrew calendar. It provides a series of date-based calculations and allows you to convert between "NSDate" and "nsdatecomponents" objects.
• Nsdatecomponents-Allows you to get a specific content of date, such as hours, minutes, years, days, and so on.
• Nstimezone-Represents a specific time zone information that can help compute tasks across time zones.

Code Analysis

Say less nonsense, Show me the Code

/**
     * Calendar
     */
    //Gregorian calendar
    NSCalendar * calendar = [[NSCalendar alloc] initWithCalendarIdentifier: NSCalendarIdentifierGregorian];
    NSDate * date = [NSDate new];
    NSLog (@ "% ld-% ld-% ld",
    [calendar component: NSCalendarUnitYear fromDate: date],
    [calendar component: NSCalendarUnitMonth fromDate: date],
    [calendar component: NSCalendarUnitDay fromDate: date]);
    // Gregorian calendar: 2018-5-9
    
    //Buddhist calendar
    calendar = [[NSCalendar alloc] initWithCalendarIdentifier: NSCalendarIdentifierBuddhist];
    NSLog (@ "% ld-% ld-% ld",
    [calendar component: NSCalendarUnitYear fromDate: date],
    [calendar component: NSCalendarUnitMonth fromDate: date],
    [calendar component: NSCalendarUnitDay fromDate: date]);
    // Buddhist calendar: 2561-5-9
    
    // Japanese calendar
    calendar = [[NSCalendar alloc] initWithCalendarIdentifier: NSCalendarIdentifierJapanese];
    NSLog (@ "% ld-% ld-% ld",
    [calendar component: NSCalendarUnitYear fromDate: date],
    [calendar component: NSCalendarUnitMonth fromDate: date],
    [calendar component: NSCalendarUnitDay fromDate: date]);
    // Japanese calendar: 30-5-9
    
    /**
     * Region
     */
    NSDateFormatter * dateFormatter = [[NSDateFormatter alloc] init];
    [dateFormatter setDateStyle: NSDateFormatterLongStyle];
    [dateFormatter setTimeStyle: NSDateFormatterLongStyle];
    NSString * formattedDateString = [dateFormatter stringFromDate: date];
    NSLog (@ "Default Locale Formatted Date:% @", formattedDateString);
    // The system is a Gregorian calendar: Default Locale Formatted Date: 9 May 2018 at 4:25:06 PM GMT + 8
    // The system is a Buddhist calendar: Default Locale Formatted Date: 9 May 2561 BE at 4:21:29 PM GMT + 8
    
    // Chinese Locale
    dateFormatter.locale = [[NSLocale alloc] initWithLocaleIdentifier: @ "zh_CN"];
    formattedDateString = [dateFormatter stringFromDate: date];
    NSLog (@ "ZH Locale Formatted Date:% @", formattedDateString);
    // ZH Locale Formatted Date: May 9, 2018 GMT + 8 PM 4:21:29 PM
    
    /**
     * Time zone
     */
    dateFormatter.timeZone = [NSTimeZone timeZoneWithName: @ "GMT"];
    formattedDateString = [dateFormatter stringFromDate: date];
    NSLog (@ "GMT Timezone Formatted Date:% @", formattedDateString);
    // GMT Timezone Formatted Date: May 9, 2018 GMT 8:21:29 AM
    
    /**
     * NSDateComponents
     */
    // Yearless date
    NSDateComponents * components = [[NSDateComponents alloc] init];
    [components setMonth: 11];
    [components setDay: 7];
    NSCalendar * gregorian = [[NSCalendar alloc]
                             initWithCalendarIdentifier: NSCalendarIdentifierGregorian];
    NSDate * birthday = [gregorian dateFromComponents: components];
    formattedDateString = [dateFormatter stringFromDate: birthday];
    NSLog (@ "GMT Timezone Formatted Date:% @", formattedDateString);
    // GMT Timezone Formatted Date: November 6, 1st GMT 3:54:17 PM 

Javascript

A Date object about JavaScript can refer to the following links:
Understanding Date and Time in JavaScript
JavaScript Date Objects

Get Date Property

 
const birthday = new Date(1980, 6, 31);
birthday.getFullYear(); // 1980
birthday.getMonth(); // 6
birthday.getDate(); // 31
birthday.getDay(); // 4
birthday.getHours(); // 0
birthday.getMinutes(); // 0
birthday.getSeconds(); // 0
birthday.getMilliseconds(); // 0
birthday.getTime(); // 333849600000 (for GMT)

Date formatting

 
var options = { weekday: ‘long‘, year: ‘numeric‘, month: ‘long‘, day: ‘numeric‘ }; var today  = new Date();

today.toLocaleDateString("en-US"); // 5/9/2018
today.toLocaleDateString("en-US",options); // Wednesday, May 9, 2018
today.toLocaleDateString("hi-IN", options); // ??????, 9 ?? 2018

Moment.js

Moment.js-parse, validate, manipulate, and display dates and times in JavaScript. Moment is a very powerful JavaScript time-and-date library that is a good extension of native objects.

 
//Format
moment().format(‘MMMM Do YYYY, h:mm:ss a‘); // May 9th 2018, 8:05:15 pm //Calendar Time
moment().add(10, ‘days‘).calendar(); //Multiple Locale Support
moment.locale(); // en //TimeZone var jun = moment("2014-06-01T12:00:00Z"); var dec = moment("2014-12-01T12:00:00Z");

jun.tz(‘America/Los_Angeles‘).format(‘ha z‘); // 5am PDT
dec.tz(‘America/Los_Angeles‘).format(‘ha z‘); // 4am PST

There is also a newer, more modern time-date library: Luxon, you can try it.

An article thoroughly understand iOS, JS time and date (date, Calendar, Locale, TimeZone)