Keychain SecItemUpdate returning errSecParam

Question

I can add items to the keychain, I can even read them out.

However, I'm struggling to use SecItemUpdate to update a value, and seem to get errSecParam returned every time.

To do so I'm creating the following query and attributes (very likely to be an issue here)

let query: [String: Any] = [kSecAttrAccount as String : "MyString",
    kSecValueData as String: "test2".data(using: .utf16)!,
    kSecMatchLimit as String  : kSecMatchLimitOne
]

let attributes: [String: Any] = [kSecAttrAccount as String: "aa",
                                         kSecValueData as String: data]

which is then used to update

SecItemUpdate(query as CFDictionary, attributes as CFDictionary)

Answer 1

It should be specified class in query and not data (for update), so, for example, to add/update password in keychain it should be as following

// adding item
let addQuery: [CFString: Any] = [
    kSecClass: kSecClassGenericPassword,
    kSecAttrService: service as CFString,        // eg. "www.mysite.com"
    kSecAttrAccount: name as CFString            // eg. "user"
    kSecValueData: password.data(using: .utf8)   // eg. "password"
] as CFDictionary

if errSecSuccess != SecItemAdd(addQuery, nil) { 
    // report error here
}

// updating item (same query is for SecItemDelete)

let updateQuery: [CFString: Any] = [
    kSecClass: kSecClassGenericPassword,
    kSecAttrService: service as CFString,        // eg. "www.mysite.com"
    kSecAttrAccount: name as CFString            // eg. "user"
] as CFDictionary

let newAttributes = [
    kSecAttrAccount: newName as CFString            // eg. "user1"
    kSecValueData: newPassword.data(using: .utf8)   // eg. "password1"
] as CFDictionary

if errSecSuccess != SecItemUpdate(updateQuery, newAttributes) {
   // report error here
}