CODEWITHSUNDEEP
iosencryptionswiftrsaunmanaged
eharo2
eharo2

Reputation: 2642

Can´t get the SecKey UnsafeMutablePointer in iOS Swift

I am working in a project in swift, involving RSA Encryption, and I am stuck with a pointer problem as follows:

I have a global var publicKey: SecKey? optional value, and I need to get the UnsafeMutablePointer<Unmanaged<SecKey>?> pointer to it, that is the data type required in the SecKeyGeneratePair function.

I am trying to define the pointer as:

var keyPointer = UnsafeMutablePointer<Unmanaged<SecKey>?>(publicKey!)

But the compiler complains with a Cannot invoke 'init' with an argument of type @lvalue SecKey error

According to the Using Swift with Cocoa and Objective-C book, In the Core Foundation and Unmanaged Objects section, it states that the Unmanaged<T> structure provides 2 methods takeUnretainedValue() and takeRetainedValue(). but trying to implement them, gives the following error

var keyPointer = UnsafeMutablePointer<Unmanaged<SecKey>?>(publicKey!.takeRetainedValue())

'SecKey' does not have a member named 'takeRetainedValue'

Any help to work this out will be appreciated

Upvotes: 1

Views: 1573

Answers (2)

Serg
Serg

Reputation: 11

for Swift 2.1 it isn't working with Unmanaged, the right version is:

var publicKey: SecKey?
var privateKey: SecKey?

let dic:[String:String] = [kSecAttrKeyType:kSecAttrKeyTypeRSA, kSecAttrKeySizeInBits:"2048"]
SecKeyGeneratePair(dic, &publicKey, &privateKey)

Upvotes: 1

rintaro
rintaro

Reputation: 51911

Try this:

var publicKey: SecKey?
var privateKey: SecKey?

var publicKeyUnManaged:Unmanaged<SecKey>?
var privateKeyUnManaged:Unmanaged<SecKey>?
let dic:[String:String] = [kSecAttrKeyType:kSecAttrKeyTypeRSA, kSecAttrKeySizeInBits:"2048"]
SecKeyGeneratePair(dic, &publicKeyUnManaged, &privateKeyUnManaged)

publicKey = publicKeyUnManaged?.takeRetainedValue()
privateKey = privateKeyUnManaged?.takeRetainedValue()

You don't have to create UnsafeMutablePointer<Unmanaged<SecKey>?> manually. As mentioned in this document,

When a function is declared as taking an UnsafeMutablePointer argument, it can accept any of the following:

  • nil, which is passed as a null pointer
  • An UnsafeMutablePointer value
  • An in-out expression whose operand is a stored lvalue of type Type, which is passed as the address of the lvalue
  • An in-out [Type] value, which is passed as a pointer to the start of the array, and lifetime-extended for the duration of the call

In this case, we can use 3rd "in-out" expression.

Upvotes: 5

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