我正在看一段代码，偶然发现timeIntervalBetween1970AndReferenceDate和timeIntervalSinceReferenceDate的用法。
代码返回以毫秒为单位的时间戳：
return (Date.timeIntervalBetween1970AndReferenceDate + date.timeIntervalSinceReferenceDate) * 1000
这不等于：
return date.timeIntervalSince1970 * 1000
最佳答案
确实，没有区别。 Date具有type属性
public static let timeIntervalBetween1970AndReferenceDate: TimeInterval
// The number of seconds from 1 January 1970 to the reference date, 1 January 2001
和实例属性
public var timeIntervalSinceReferenceDate: TimeInterval { get }
// The interval between the date value and 00:00:00 UTC on 1 January 2001.
public var timeIntervalSince1970: TimeInterval { get }
// The interval between the date value and 00:00:00 UTC on 1 January 1970.
这意味着对于任何
date类型的值Date，标识Date.timeIntervalBetween1970AndReferenceDate + date.timeIntervalSinceReferenceDate
== date.timeIntervalSince1970
持有。实际上，正如我们在Date.swift#L111中所见，
timeIntervalSince1970被实现为public var timeIntervalSince1970: TimeInterval {
return self.timeIntervalSinceReferenceDate + Date.timeIntervalBetween1970AndReferenceDate
}
关于swift - 是timeIntervalBetween1970AndReferenceDate + timeIntervalSinceReferenceDate = timeIntervalSince1970，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/51107324/