将日期(绝对时间)转换为 Swift 中的数据作为数据通过网络发送/接收? [英] Convert a Date (absolute time) to be sent/received across the network as Data in Swift?

问题描述

我正在寻找一种快速生成时间戳的方法.

I am looking for a Swifty way to generate a timestamp.

我的 macOS 应用记录了一些数据，并在数据创建时间上加盖戳记.然后数据将通过网络发送(作为 Data)以在 iPad 上重建.

My macOS app logs some data and stamps it with the time the data was created. The data will then be sent across the network (as Data) to be reconstructed on an iPad.

是否有任何 Swift 类可以生成时间戳?NSDate?NSTimeIntervalSince1970?CFAbsoluteTimeGetCurrent()

Is there any Swift class that will work to generate the timestamp? NSDate? NSTimeIntervalSince1970? CFAbsoluteTimeGetCurrent()

要求是:

1. 以尽可能少的字节存储时间戳(首选Int)
2. 与真实地球时间有一些相似之处(我宁愿不生成我的自己的时间格式)
3. 毫秒精度
4. 快速构建
5. iOS 9+、macOS 10.10+

推荐答案

您可以发送您的 Date 将其转换为 Data(8 字节浮点数)并返回到日期如下:

You can send your Date converting it to Data (8-bytes floating point) and back to Date as follow:

extension Numeric {
    var data: Data {
        var source = self
        return .init(bytes: &source, count: MemoryLayout<Self>.size)
    }
    init<D: DataProtocol>(_ data: D) {
        var value: Self = .zero
        let size = withUnsafeMutableBytes(of: &value, { data.copyBytes(to: $0)} )
        assert(size == MemoryLayout.size(ofValue: value))
        self = value
    }
}

<小时>

extension UInt64 {
    var bitPattern: Double { .init(bitPattern: self) }
}

<小时>

extension Date {
    var data: Data { timeIntervalSinceReferenceDate.bitPattern.littleEndian.data }
    init<D: DataProtocol>(data: D) {
        self.init(timeIntervalSinceReferenceDate: data.timeIntervalSinceReferenceDate)
    }
}

<小时>

extension DataProtocol {
    func value<N: Numeric>() -> N { .init(self) }
    var uint64: UInt64 { value() }
    var timeIntervalSinceReferenceDate: TimeInterval { uint64.littleEndian.bitPattern }
    var date: Date { .init(data: self) }
}

<小时>

游乐场测试

---

Playground Testing

let date = Date()            // "Nov 15, 2019 at 12:13 PM"
let data = date.data         // 8 bytes
print(Array(data))           // "[25, 232, 158, 22, 124, 191, 193, 65]\n"
let loadedDate = data.date   // "Nov 15, 2019 at 12:13 PM"
print(date == loadedDate)    // "true"

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