SwiftDate与数据计算

Question

我在计算宠物活着的时间和时间。我用的是SwiftDate。因此，我让用户选择一个生日，并将其与当前日期进行比较。

我不想比较时间..。因此，出生日期和当前日期都应该有相同的时间。

我的代码是：

let greg = Calendar(identifier: .gregorian)
var date1 = birthday // from datepicker
var date2 = Date()
var components1 = greg.dateComponents([.year, .month, .day, .hour, .minute, .second], from: date1)
var components2 = greg.dateComponents([.year, .month, .day, .hour, .minute, .second], from: date2)
components1.hour = 15
components1.minute = 0
components1.second = 0
components2.hour = 15
components2.minute = 0
components2.second = 0
date1 = greg.date(from: components1)!
date2 = greg.date(from: components2)!

let daysAlive = (date2 - date1).in(.day)
let weeksAlive = Int(weeksAlive! / 7)
let restDays = daysAlive! - (weeksAlive * 7)
let aLive = "Age: \(weeksAlive) wk, \(restDays) d (\(daysAlive!) d)"

产出为“年龄: 28周，3天(199天)”

密码有效..。但我怎么能重构它呢？有什么更简单的方法来为两个给定的日期设定“同一时间”呢？

Answer 1

忽略时间，只需省略.hour、.minute和.second的组件

let components1 = greg.dateComponents([.year, .month, .day], from: date1)
let components2 = greg.dateComponents([.year, .month, .day], from: date2)

date1 = greg.date(from: components1)!
date2 = greg.date(from: components2)!

这是一个更简单的解决方案，没有任何第三方库。它计算weekOfMonth和day的差异一次，用Calendar方法dateComponents(:from:to:计算day的差异一次。不需要额外的数学。

let greg = Calendar(identifier: .gregorian)
var date1 = greg.date(from: DateComponents(year: 2017, month: 6, day: 25))!
var date2 = Date()
var components1 = greg.dateComponents([.year, .month, .day], from: date1)
var components2 = greg.dateComponents([.year, .month, .day], from: date2)

let weeksAndDays = greg.dateComponents([.weekOfMonth, .day], from: components1, to: components2)
let justDays = greg.dateComponents([.day], from: components1, to: components2)

let aLive = "Age: \(weeksAndDays.weekOfMonth!) wk, \(weeksAndDays.day!) d (\(justDays.day!) d)"
// "Age: 28 wk, 3 d (199 d)"

Answer 2

如果你不关心时差，为什么不把时间完全排除在外呢？它将为您提供相同的输出，并且只会使您避免输入缺省时间值，然后对函数的其余部分忽略它们：

let greg = Calendar(identifier: .gregorian)
var date1 = birthday // from datepicker
var date2 = Date()
var components1 = greg.dateComponents([.year, .month, .day], from: date1)
var components2 = greg.dateComponents([.year, .month, .day], from: date2)
date1 = greg.date(from: components1)!
date2 = greg.date(from: components2)!

let daysAlive = (date2 - date1).in(.day)
let weeksAlive = Int(weeksAlive! / 7)
let restDays = daysAlive! - (weeksAlive * 7)
let aLive = "Age: \(weeksAlive) wk, \(restDays) d (\(daysAlive!) d)"