Swift 3.0 从数据中检索 int

Question

代码如下：

func match(_ match: GKMatch, didReceive data: Data, fromRemotePlayer player: GKPlayer){

    if(gameOver){
        return;
    }
    if(variables.background){
        match.disconnect()
    }

    if(!randReceived){
        levelLabel.text = "Match Against "+(match.players[0] ).displayName!
        self.addChild(levelLabel)

        randReceived=true
        var number: Int = 0
        number = data.withUnsafeBytes {
            (pointer: UnsafePointer<Int>) -> Int in
            return pointer.pointee
        }
    }
}

它给出了一个错误 "Value of type Data has no member 'withUnsafeBytes'"。我该如何解决这个问题？

Answer 1

您的代码有效。我在 playground 中尝试了 essential 部分没有任何问题:

var test: Int = 1000
let data = Data(bytes: &test, count: MemoryLayout<Int>.size)

var number: Int = 0
number = data.withUnsafeBytes { (pointer: UnsafePointer<Int>) -> Int in
    return pointer.pointee
}

在你的情况下，错误是：

Value of type Data has no member 'withUnsafeBytes

基本上这样的错误表明它无法在 Data 对象上找到该特定函数。
您可能已将自己的 Data 定义为覆盖了 Foundation.

中定义的 Data 结构的 class/struct/something

Option-Click 并确认它说：

Declared in Foundation

Answer 2

请试试这个，它会帮助你

extension Data {
    func copyBytes<T>(as _: T.Type) -> [T] {
        return withUnsafeBytes { (bytes: UnsafePointer<T>) in
            Array(UnsafeBufferPointer(start: bytes, count: count / MemoryLayout<T>.stride))
        }
    }
}

或者

let size = MemoryLayout<Int16>.stride
let data = Data(bytes: [1, 0, 2, 0, 3, 0]) // little endian for 16-bit values
let int16s = data.withUnsafeBytes { (bytes: UnsafePointer<Int16>) in
    Array(UnsafeBufferPointer(start: bytes, count: data.count / size))
}

Swift 3.0 从数据中检索 int

Swift 3.0 retrieving int from Data

ios

swift3