如何计算两个日期之间的差额？

如何计算2010年1月1日至2010年2月3日之间的日期？

NSDate *date1 = [NSDate dateWithString:@"2010-01-01 00:00:00 +0000"];
NSDate *date2 = [NSDate dateWithString:@"2010-02-03 00:00:00 +0000"];

NSTimeInterval secondsBetween = [date2 timeIntervalSinceDate:date1];

int numberOfDays = secondsBetween / 86400;

NSLog(@"There are %d days in between the two dates.", numberOfDays);

编辑：

请记住，NSDate对象代表确切的时刻，它们没有任何关联的时区信息。当您使用例如一个字符串转换为日期NSDateFormatter时，NSDateFormatter从配置的时区的时间转换。因此，两个NSDate对象之间的秒数始终是时区不可知的。

此外，本文档还指定可可的时间实现方式不包含leap秒，因此，如果您需要这种准确性，则需要滚动自己的实现方式。

您可能要使用以下内容：

NSDateComponents *components;
NSInteger days;

components = [[NSCalendar currentCalendar] components: NSDayCalendarUnit 
        fromDate: startDate toDate: endDate options: 0];
days = [components day];

我相信这种方法可以解决诸如夏令时变化之类的日期。

NSTimeInterval diff = [date2 timeIntervalSinceDate:date1]; // in seconds

在date1和date2在NSDate。

另外，请注意以下定义NSTimeInterval：

typedef double NSTimeInterval;

签出这个。它使用iOS日历来计算夏令时和leap年，您可以将字符串和条件更改为包括小时和天的分钟。

+(NSString*)remaningTime:(NSDate*)startDate endDate:(NSDate*)endDate
{
    NSDateComponents *components;
    NSInteger days;
    NSInteger hour;
    NSInteger minutes;
    NSString *durationString;

    components = [[NSCalendar currentCalendar] components: NSCalendarUnitDay|NSCalendarUnitHour|NSCalendarUnitMinute fromDate: startDate toDate: endDate options: 0];

    days = [components day];
    hour = [components hour];
    minutes = [components minute];

    if(days>0)
    {
        if(days>1)
            durationString=[NSString stringWithFormat:@"%d days",days];
        else
            durationString=[NSString stringWithFormat:@"%d day",days];
        return durationString;
    }
    if(hour>0)
    {        
        if(hour>1)
            durationString=[NSString stringWithFormat:@"%d hours",hour];
        else
            durationString=[NSString stringWithFormat:@"%d hour",hour];
        return durationString;
    }
    if(minutes>0)
    {
        if(minutes>1)
            durationString = [NSString stringWithFormat:@"%d minutes",minutes];
        else
            durationString = [NSString stringWithFormat:@"%d minute",minutes];

        return durationString;
    }
    return @""; 
}

使用Swift 5和iOS 12，根据您的需要，您可以使用以下两种方法之一来查找两天之间的日期差异。

＃1。使用Calendar的dateComponents(_:from:to:)方法

import Foundation

let calendar = Calendar.current

let startDate = calendar.date(from: DateComponents(year: 2010, month: 11, day: 22))!
let endDate = calendar.date(from: DateComponents(year: 2015, month: 5, day: 1))!

let dateComponents = calendar.dateComponents([Calendar.Component.day], from: startDate, to: endDate)

print(dateComponents) // prints: day: 1621 isLeapMonth: false
print(String(describing: dateComponents.day)) // prints: Optional(1621)

＃2。使用DateComponentsFormatter的string(from:to:)方法

import Foundation

let calendar = Calendar.current

let startDate = calendar.date(from: DateComponents(year: 2010, month: 11, day: 22))!
let endDate = calendar.date(from: DateComponents(year: 2015, month: 5, day: 1))!

let formatter = DateComponentsFormatter()
formatter.unitsStyle = .full
formatter.allowedUnits = [NSCalendar.Unit.day]

let elapsedTime = formatter.string(from: startDate, to: endDate)
print(String(describing: elapsedTime)) // prints: Optional("1,621 days")

Swift 4
试试看，看一下（带字符串的日期范围）：

// Start & End date string
let startingAt = "01/01/2018"
let endingAt = "08/03/2018"

// Sample date formatter
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "dd/MM/yyyy"

// start and end date object from string dates
var startDate = dateFormatter.date(from: startingAt) ?? Date()
let endDate = dateFormatter.date(from: endingAt) ?? Date()


// Actual operational logic
var dateRange: [String] = []
while startDate <= endDate {
    let stringDate = dateFormatter.string(from: startDate)
    startDate = Calendar.current.date(byAdding: .day, value: 1, to: startDate) ?? Date()
    dateRange.append(stringDate)
}

print("Resulting Array - \(dateRange)")

迅捷3

var date1 = Date(string: "2010-01-01 00:00:00 +0000")
var date2 = Date(string: "2010-02-03 00:00:00 +0000")
var secondsBetween: TimeInterval = date2.timeIntervalSince(date1)
var numberOfDays: Int = secondsBetween / 86400
print(numberOfDays)

您可以通过以秒为单位转换日期并采用自1970年以来的时间间隔来找到差异，然后可以找到两个日期之间的差异。

要发现差异，您需要获取当前日期和将来的日期。在以下情况下，我以2天作为未来日期的示例。计算方式：

2 days* 24 hours* 60 minutes* 60 seconds。我们预计2天的秒数为172,800。

// Set the current and future date
let now = Date()
let nowPlus2Days = Date(timeInterval: 2*24*60*60, since: now)

// Get the number of seconds between these two dates
let secondsInterval = DateInterval(start: now, end: nowPlus2Days).duration

print(secondsInterval) // 172800.0