ios - 将 UnsafeMutablePointer 转换为 UnsafeMutableRawPointer

Question

我在更新到 swift 3.0 时遇到了一些问题。我有以下代码:

  // Retrieve the Device GUID
        let device = UIDevice.current
        let uuid = device.identifierForVendor
        let mutableData = NSMutableData(length: 16)
        (uuid! as NSUUID).getBytes(UnsafeMutablePointer(mutableData!.mutableBytes))

        // Verify the hash
        var hash = Array<UInt8>(repeating: 0, count: 20)
        var ctx = SHA_CTX()
        SHA1_Init(&ctx)
        SHA1_Update(&ctx, mutableData!.bytes, mutableData!.length)
        SHA1_Update(&ctx, (opaqueData1! as NSData).bytes, opaqueData1!.count)
        SHA1_Update(&ctx, (bundleIdData1! as NSData).bytes, bundleIdData1!.count)
        SHA1_Final(&hash, &ctx)
        let computedHashData1 = Data(bytes: UnsafePointer(&hash), count: 20)

我的第一个问题是代码行:

(uuid! as NSUUID).getBytes(UnsafeMutablePointer(mutableData!.mutableBytes))

mutableData!.mutableBytes 现在返回一个 UnsafeMutableRawPointer 并且编译器提示“无法使用类型为 '(UnsafeMutableRawPointer)' 的参数调用类型 'UnsafeMutablePointer<_> 的初始化程序” 现在我一直在尝试将它们转换为相同的类型但没有成功。

我的第二个问题与该行有关:

let computedHashData1 = Data(bytes: UnsafePointer(&hash), count: 20)

此行会导致编译器错误“‘init’的使用不明确”

Answer 1

你的第一期，你可以这样写:

    (uuid! as NSUUID).getBytes(mutableData!.mutableBytes.assumingMemoryBound(to: UInt8.self))

但如果你能接受Data具有相同的原始 UUID 字节，您可以将其写为:

    var uuidBytes = uuid!.uuid
    let data = Data(bytes: &uuidBytes, count: MemoryLayout.size(ofValue: uuidBytes))

<小时/>

您的第二期，在 Data.init(bytes:count:) ，第一个参数的类型为UnsafeRawPointer ，您可以向其传递任意类型的 Unsafe(Mutable)Pointer s。

Using Swift with Cocoa and Objective-C (Swift 3)

检查 Pointers 的常量指针部分.

When a function is declared as taking an UnsafeRawPointer argument, it can accept the same operands as UnsafePointer<Type> for any type Type.

您无需强制转换指针类型。

    let computedHashData1 = Data(bytes: &hash, count: 20)