如何从 NSDate(timeIntervalSince1970) 转换为 NSDate()? [英] How to convert from NSDate(timeIntervalSince1970 to NSDate()?

问题描述

这是我的代码.但是一个错误说，无法使用类型为参数列表调用 dateComponent...

This is my code. But an error said, cannot invoke dateComponent with an argument list of type...

 let fromDate = NSDate(timeIntervalSince1970: TimeInterval(tweetsArray[indexPath.row].timestamp)!)

        let toDate = NSDate()

        let components : NSCalendar.Unit = [.second, .minute, .hour, .day, .weekOfMonth]

        let differenceOfDate = NSCalendar.current.dateComponents(components, from: fromDate, to: toDate)

推荐答案

在 Swift 3 中，NSCalendar.current 返回一个 Calendar，它是Foundation NSCalendar 类型的 Swift 值包装器类型.

In Swift 3, NSCalendar.current returns a Calendar, which is the Swift value wrapper type for the Foundation NSCalendar type.

dateComponents() 接受一个 Set 和两个 Date 参数.Date 是 NSDate 的 Swift 值包装器类型.

dateComponents() takes a Set<Calendar.Component> and two Date arguments. Date is the Swift value wrapper type for NSDate.

当现有的 Foundation API 导入 Swift 时，类型会自动桥接，这就是为什么 NSCalendar.current返回 Calender 而不是 NSCalendar.

When existing Foundation APIs are imported into Swift, the types are bridged automatically, that why NSCalendar.current returns a Calender and not NSCalendar.

值类型在 Swift 3 中是首选的，因为它们提供适当的值语义并使用 let 和 var 代替不可变和可变变体.

The values types are preferred in Swift 3 because they provide proper value semantics and use let and var instead of immutable and mutable variants.

综合起来:

let fromDate = Date(timeIntervalSince1970: ...)
let toDate = Date()
let components = Set<Calendar.Component>([.second, .minute, .hour, .day, .weekOfMonth])
let differenceOfDate = Calendar.current.dateComponents(components, from: fromDate, to: toDate)

有关 Swift 3 值包装器类型的更多信息和它们对应的基础类型，见SE-0069 可变性和基础值类型，或桥接类型"部分参考.

For more information about Swift 3 value wrapper types and their corresponding Foundation types, see SE-0069 Mutability and Foundation Value Types, or the section "Bridged Types" in Working with Cocoa Frameworks in the "Using Swift with Cocoa and Objective-C" reference.

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