Reading Data into a Struct in Swift

Question

I\'m trying to read bare Data into a Swift 4 struct using the withUnsafeBytes method. The problem

The network UDP packet has t

Answer 1

Following on Leo Dabus answer, I created a slightly more readable constructor:

extension Data {
    func object(at index: Index) -> T {
        subdata(in: index ..< index.advanced(by: MemoryLayout.size))
            .withUnsafeBytes { $0.load(as: T.self) }
    }
}

---

struct XPLBeacon {
    var majorVersion: UInt8
    var minorVersion: UInt8
    var applicationHostId: UInt32
    var versionNumber: UInt32

    init(data: Data) {
        var index = data.startIndex
        majorVersion = data.object(at: index)

        index += MemoryLayout.size(ofValue: majorVersion)
        minorVersion = data.object(at: index)

        index += MemoryLayout.size(ofValue: minorVersion)
        applicationHostId = data.object(at: index)

        index += MemoryLayout.size(ofValue: applicationHostId)
        versionNumber = data.object(at: index)
    }
}

What is not part of this is of course the checking for the correctness of the data. As other mentioned in comments, this could be done either by having a failable init method or by throwing an Error.