计算Objective-C中两个日期之间的天数

Question

可能重复：How can I compare two dates, return a number of days

例如，我有两个日期（作为NSString，格式为“ yyyy-mm-dd”）：

NSString *start = "2010-11-01";
NSString *end = "2010-12-01";

我想实施：

- (int)numberOfDaysBetween:(NSString *)startDate and:(NSString *)endDate {

}

Answer 1

NSString *start = @"2010-09-01";
NSString *end = @"2010-12-01";

NSDateFormatter *f = [[NSDateFormatter alloc] init];
[f setDateFormat:@"yyyy-MM-dd"];
NSDate *startDate = [f dateFromString:start];
NSDate *endDate = [f dateFromString:end];

NSCalendar *gregorianCalendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSCalendarIdentifierGregorian];
NSDateComponents *components = [gregorianCalendar components:NSCalendarUnitDay
                                                    fromDate:startDate
                                                      toDate:endDate
                                                     options:0];

[components现在保留了区别。

NSLog(@"%ld", [components day]);

Answer 2

有完整的日期和时间编程指南。这是relevant section，可为您提供操作提示。

这是示例代码在另一个问题中的来源。

尝试以此为基础编写一些内容，如果有特定问题，请再回来。

编辑

好。这是我将以最基本的形式编写代码的方式。

首先，我将扩展NSDate。

头文件：

//  NSDate+ADNExtensions.h

#import <Cocoa/Cocoa.h>


@interface NSDate (ADNExtensions)

- (NSInteger)numberOfDaysUntil:(NSDate *)aDate;

@end

实施文件：

//  NSDate+ADNExtensions.m

#import "NSDate+ADNExtensions.h"


@implementation NSDate (ADNExtensions)


- (NSInteger)numberOfDaysUntil:(NSDate *)aDate {
    NSCalendar *gregorianCalendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];

    NSDateComponents *components = [gregorianCalendar components:NSDayCalendarUnit fromDate:self toDate:aDate options:0];

    return [components day];
}


@end

这是非常粗糙的代码。没有错误检查或验证第二个日期晚于第一个日期。

然后，我将像这样使用它（在64位垃圾收集环境中运行）：

NSDate *startDate = [NSDate dateWithString:@"2010-11-01 00:00:00 +0000"];
NSDate *endDate = [NSDate dateWithString:@"2010-11-02 00:00:00 +0000"];

NSInteger difference = [startDate numberOfDaysUntil:endDate];

NSLog(@"Diff = %ld", difference);

这真是太遗憾了，因为通过发布代码和错误的输出并获得更多具体的帮助，您将学到很多东西。但是，如果您只是想成为剪切粘贴的程序员，那么，接受此代码，祝您好运。

Answer 3

此代码在Swift 2中似乎很好用：

func daysBetweenDate(startDate: NSDate, endDate: NSDate) -> Int
{
    let calendar = NSCalendar.currentCalendar()

    let components = calendar.components([.Day], fromDate: startDate, toDate: endDate, options: [])

    return components.day
}

Answer 4

Swift 4实现

方法调用：

let numberOfDays = daysBetweenDates(startDate: fileCreatedDate,endDate: date)

方法实现：

 func daysBetweenDates(startDate: Date, endDate: Date) -> Int {
        let daysBetween = Calendar.current.dateComponents([.day], from: startDate, to: endDate)
        print(daysBetween.day!)
        return daysBetween.day!
  }

目标C实现：

方法调用：

int numberOfDaysSinceFileCreation = [self daysBetweenDates: fileCreatedDate
                                                                   currentDate: today];

方法实现：

- (int) daysBetweenDates: (NSDate *)startDate currentDate: (NSDate *)endDate
{
    NSCalendar *calendar = [NSCalendar currentCalendar];
    NSDateComponents *dateComponent = [calendar components:NSCalendarUnitDay fromDate:startDate toDate:endDate options:0];

    int totalDays = (int)dateComponent.day;
    return totalDays;

}

Answer 5

ObjC代码：

NSDateComponents *dateComponent = [calender components:NSCalendarUnitDay fromDate:startDate toDate:endDate options:0];

结果：

int totalDays = (int)dateComponent.day;

Answer 6

Swift 3：

let formatter = DateFormatter()
formatter.dateFormat = "yyyy-MM-dd"
let start = formatter.date(from: "2010-09-01")!
let end = formatter.date(from: "2010-12-01")!
let days = Calendar.current.dateComponents([.day], from: start, to: end).day!