斯威夫特：按日期比较日期

Question

我试着比较两天忽略时间。所以我用

calendar.compare(date1, to: date2, toGranularity: .day)

但是当将字符串日期传输到Date类型时，它将转换为UTC。所以它将从2016年1月1日0:05“移动”到2015年12月31日晚上11:05。每日比较时，这仅包括剩余的小时。在转换之前它是24小时。有什么想法不费吹灰之力地处理这个问题？

此外： 代码：

var dateFormatter = DateFormatter()
dateFormatter.dateFormat = "dd-MM-yyyy hh:mm"
var date1 : Date = dateFormatter.date(from:  "01-01-2016 00:05")!
var date2 = dateFormatter.date(from:  "01-01-2016 03:30")

if let dateFromString = dateFormatter.date(from:  "01-01-2016 00:05") {
    print(dateFromString)
    dateFormatter.timeZone = TimeZone(secondsFromGMT: 0)
    let stringFromDate = dateFormatter.string(from: dateFromString)
}


Calendar.current.compare(date1, to: date2!, toGranularity: .day) == .orderedSame

Answer 1

详细

• Xcode 10.1（10B61，Sw​​ift 4.2
• Xcode 10.2.1（10E1001），Swift 5

观

基于使用dateComponents(_:from:to:)函数

解决方案

import Foundation

extension Date {

    func totalDistance(from date: Date, resultIn component: Calendar.Component) -> Int? {
        return Calendar.current.dateComponents([component], from: self, to: date).value(for: component)
    }

    func compare(with date: Date, only component: Calendar.Component) -> Int {
        let days1 = Calendar.current.component(component, from: self)
        let days2 = Calendar.current.component(component, from: date)
        return days1 - days2
    }

    func hasSame(_ component: Calendar.Component, as date: Date) -> Bool {
        return self.compare(with: date, only: component) == 0
    }
}

完整样本

  

不要忘记在此处输入解决方案代码（上图）

var dateFormatter = DateFormatter()
dateFormatter.dateFormat = "dd-MM-yyyy hh:mm:ss"
//dateFormatter.timeZone = TimeZone(secondsFromGMT: 0)

let smallerDate = dateFormatter.date(from: "01-01-2012 00:05:01")!
let biggerDate  = dateFormatter.date(from: "03-12-2019 09:30:01")!

print(smallerDate.totalDistance(from: biggerDate, resultIn: .day))      // Optional(2893)
print(biggerDate.totalDistance(from: smallerDate, resultIn: .day))      // Optional(-2893)
print(smallerDate.totalDistance(from: biggerDate, resultIn: .year))     // Optional(7)
print(biggerDate.totalDistance(from: smallerDate, resultIn: .year))     // Optional(7)
print(smallerDate.totalDistance(from: biggerDate, resultIn: .hour))     // Optional(69441)
print(biggerDate.totalDistance(from: smallerDate, resultIn: .hour))     // Optional(-69441)

print(smallerDate.compare(with: biggerDate, only: .day))    // -2
print(biggerDate.compare(with: smallerDate, only: .day))    // 2
print(smallerDate.compare(with: biggerDate, only: .year))   // -7
print(biggerDate.compare(with: smallerDate, only: .year))   // 7
print(smallerDate.compare(with: biggerDate, only: .hour))   // -9
print(biggerDate.compare(with: smallerDate, only: .hour))   // 9

print(smallerDate.hasSame(.day, as: biggerDate))         // false
print(biggerDate.hasSame(.second, as: smallerDate))      // true