gistfile1.txt

// Extract the public key
var pub_key_leaf = SecTrustCopyPublicKey(trust!)

let keychainTag = "X509_TAG"

var publicKeyData : AnyObject?
var putResult : OSStatus, delResult : OSStatus = noErr

// Params for putting the key first
var putKeyParams = NSMutableDictionary()
putKeyParams[kSecClass as String] = kSecClassKey
putKeyParams[kSecAttrApplicationTag as String] = keychainTag
putKeyParams[kSecValueRef as String] =  (pub_key_leaf)
putKeyParams[kSecReturnData as String] = kCFBooleanTrue // Request the key's data to be returned too

// Params for deleting the data
var delKeyParams = NSMutableDictionary()
delKeyParams[kSecClass  as String] = kSecClassKey
delKeyParams[kSecAttrApplicationTag as String] = keychainTag
delKeyParams[kSecReturnData as String] = kCFBooleanTrue

// Put the key
putResult = SecItemAdd(putKeyParams, &publicKeyData)
// Delete the key
delResult = SecItemDelete(delKeyParams)

if ((putResult != errSecSuccess) || (delResult != errSecSuccess))
{
  publicKeyData = nil;
}
var keyString = (publicKeyData as! NSData).base64EncodedDataWithOptions(NSDataBase64EncodingOptions())